Method of Producing a Low Molecular Weight Organic Compound in a Cell

ABSTRACT

A method of producing a low molecular weight organic compound (e.g. a plant or bacteria secondary metabolite) in increased yields involving use of a microorganism cell, which comprises a gene involved in the biosynthesis pathway leading to a low molecular weight organic aglycon compound and a glycosyltransferase gene capable of glycosylating the produced aglycon.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/205,288, filed Aug. 8, 2011, which is a continuation of U.S.application Ser. No. 12/909,088, filed Oct. 21, 2010 (now U.S. Pat. No.8,105,786), which is a divisional of U.S. application Ser. No.10/561,823, filed Dec. 19, 2005 (now U.S. Pat. No. 7,846,697), which isa section 371 national filing of PCT/EP2004/051104, filed Jun. 14, 2004,which claims priority to EP 03102650.3, filed Aug. 26, 2003 and EP031018013 filed Jun. 19, 2003, all of which are hereby incorporated byreference in their entirety.

FIELD OF THE INVENTION

The present invention relates to a method of producing a low molecularweight organic compound (e.g. a plant or bacteria secondary metabolite)in increased yields involving use of a cell (e.g. a plant ormicroorganism cell), which comprises a gene involved in the biosynthesispathway leading to a low molecular weight organic aglycon compound and aglycosyltransferase gene capable of glycosylating the produced aglycon.

BACKGROUND OF THE INVENTION

Plants and microbes synthesize a large number of natural substances, inparticular secondary metabolites, with diverse and generally unclearfunction. In contrast to the primary metabolites e g. amino acids,sugars, fatty acids), which are involved in fundamental functions likemetabolism, growth, maintenance and survival, secondary metabolites arenot required for fundamental functions. Many secondary metabolites fromplants are known to act as repellents or natural pesticides in defenseagainst herbivore animals or as sexual attractants to pollinatinginsects (Grisebach, 1988, In: European Conference on Biotechnology,Scientific, technical and industrial challenges, Verona, Italy, 7-8 Nov.1988, pages 23-27), whereas fungal secondary metabolites often act asphytotoxins (Osbourn, 2001, Proceedings of the National Academy of theUSA 98: 14187-14188).

Various secondary metabolites from more than 100 different plant specieshave been shown to exert antimicrobial activity (Cowan, 1999, ClinicalMicrobiology Reviews 12: 564-582) and a large number of secondarymetabolites from common food plants are not only responsible for thetaste and color but are also believed to have health promotingactivities (Eastwood, 2001, Quarterly Journal of Medicine 94: 45-48;Drewnowski & Gomez-Cameros, 2000, American Journal of Clinical Nutrition72:1424-1435). Accordingly, these natural substances are economicallyimportant in such different fields as drugs, food additives, fragrances,pigments, and pesticides.

Secondary metabolites often accumulate in small quantities and sometimesonly in specialized cells. Hence their extraction can be difficult andinefficient. In spite of the progress in organic chemical synthesis, alarge number of these metabolites have such complex structures that theyare virtually impossible to synthesize at economic levels. Moreover, thenatural product is generally more acceptable to consumers than anartificially produced one. Consequently, industrial application of thesesubstances and their functional analogues often relies on naturalextraction from plants.

Secondary metabolites may generally be structurally qualified as lowmolecular weight organic compounds.

Industrial production of secondary metabolites or other natural and nonnatural low molecular weight organic compounds can be facilitated by abiotechnological approach By transformation of genes involved in thebiosynthesis of a desired natural product, plants or microbes can e.g.be manipulated to produce a compound not previously present in the plantor organism.

Glycosyltransferase may be defined as an enzyme which transfers residuesof sugars (galactose, xylose, rhamnose, glucose, arabinose, glucuronicacid, etc) to acceptor molecules. Acceptor molecules may be othersugars, proteins, lipids and other organic substrates. The acceptormolecule may be termed an aglycon (aglucone if sugar is glucose). Anaglycon may be defined as the non-carbohydrate part of a glycoside. Aglycoside may be defined as an organic molecule with a glycosyl group(organic chemical group derived from a sugar or polysaccharide molecule)connected to it by way of e.g. an intervening oxygen, nitrogen orsulphur atom.

These glycosylated molecules take part in diverse metabolic pathways andprocesses. The transfer of a glycosyl moiety can alter the acceptor'sbioactivity, solubility, stability, taste, scent and transportproperties e.g. within a plant or microbial cell and throughout theplant.

The art describes a number of glycosyltransferases that can glycosylatecompounds such as secondary metabolites from e.g. plants and fungi(Paquette, S. et al, Phytochemistry 62 (2003) 399-413).

WO01/07631, WO01/40491 and (Arend, J et al., Biotech. & Bioeng (2001)78:126-131) describe that at least some of these glycosyltransferasesare capable of glycosylating a number of different structurally relatedsecondary metabolites and other structurally related low molecularweight organic compounds.

Accordingly, the skilled person has at his disposal a number ofdifferent glycosyltransferases capable of glycosylating numerousdifferent secondary metabolites and other structurally related lowmolecular weight organic compounds.

Tattersall, D B et al, Science (2001) 293:1826-8 describes that theentire pathway for synthesis of the tyrosine-derived cyanogenicglucoside dhurrin [a seconday metabolite] has been transferred from theplant Sorghum bicolor to the plant Arabidopsis thaliana. The entirepathway for synthesis included two genes involved in the biosynthesispathway (CYP79A1 and CYP71E1) and a glucosyltransferase (sbHMNGT)capable of glucosylating the last intermediate p-hydroxymandelonitrile)to get the glucoside dhurrin (see FIG. 1 herein). It was demonstratedthat the transgenic Arabidopsis thaliana plant was capable of producing4 mg of dhurrin per gram of fresh weight.

Arend, J et al., Biotech. & Bioeng (2001) 78:126-131 and WO01/07631describes cloning of a glucosyltransferase from the plant Rauvolfiaserpentina. The cloned glucosyltransferase was inserted into E. colibacteria. When the aglucones hydroquinone, vanillin andp-hydroxyacetophenone were added to the medium of cultivated cells ofthe engineered E. coli, the corresponding glucosides, arbutin,vanillin-D-glucoside and picein were synthesized. They also werereleased from the cells into the surrounding medium.

Moehs, C P et al, Plant Journal (1997) 11:227-236 describes that a cDNAencoding a solanidine glucosyltransferase (SGT) was isolated frompotato. The cDNA was selected from a yeast expression library using apositive selection based on the higher toxicity of steroidal alkaloidaglycon relatively to their corresponding glycosylated forms. Theactivity of the cloned SGT was tested in an in vitro assay based onisolated recombinant produced SGT.

U.S. Pat. No. 6,372,461 describes a method for making the secondarymetabolite vanillin by use of an E. coli cell where there has beenintroduced genes involving in the biosynthesis pathway starting fromglucose and leading to vanillic acid. The recombinant E. coli canproduce vanillic acid when cultured in a medium comprising glucose. Theproduced vanillic acid is recovered from the fermentation broth andreduced to vanillin with aryl-aldehyde dehydrogenase.

SUMMARY OF THE INVENTION

The problem to be solved by the present invention is to provide a newmethod of producing in particular low molecular weight organic compoundsof interest, wherein the method provides the possibility of obtainingthe compound in higher yields.

Among other things, the solution is based on that the present inventorshave investigated and compared the following two cultivatedmicroorganisms.

-   -   (i) a microorganism comprising a gene involved in the        biosynthesis pathway leading to a low molecular weight aglycon        compound; and    -   (ii) the same microorganism but where there is also introduced a        glycosyltransferase gene capable of glycosylating the produced        aglycon to get the associated glycosylated form of the aglycon.

The inventors found that the microorganism with the glycosyltransferaseduring culture fermentation is capable of producing higher amounts ofthe glycosylated form of the aglycon as compared to the amounts of thecorresponding aglycon produced by the microorganism without theglycosyltransferase. See working examples herein for an illustrativeexamples where

-   -   (a) an E. coli cell of type (ii) above produces higher amounts        of vanillin glucoside as compared to the amounts of the        corresponding vanillin aglucone produced in a corresponding E.        coli without the glycosyltransferase (E. coli cell of type (i)        above);    -   (b) a yeast cell of type (ii) above produces higher amounts of        vanillin glucoside as compared to the amounts of the        corresponding vanillin aglucone produced in a corresponding        yeast        cell without the glycosyltransferase (yeast cell of type (i)        above);    -   (c) a yeast cell of type (ii) above produces higher amounts of        protocatechuic acid-β-D-glucoside (PAG) as compared to the        amounts of the corresponding protocatechuic acid (PA) aglucone        produced in a corresponding yeast cell without the        glycosyltransferase (yeast cell of type (i) above);    -   (d) a yeast cell of type (ii) above produces higher amounts of        dhurrin as compared to the amounts of the        p-hydroxymandelonitrile (aglycone of dhurrin. See FIG. 1)        produced in        a corresponding yeast cell without the glycosyltransferase        (yeast cell of type (i) above);    -   (e) a yeast cell of type (ii) above produces higher amounts of        glucosylated compounds (such as e.g.        p-glucosyloxy-phenylethanol, p-glucosyloxy-phenylacetonitrile,        p-glucosyloxy-benzaldehyde or glucosyl p-hydroxybenzoate)        derived from the Dhurrin biosynthesis pathway as compared to the        amounts of corresponding aglycons produced in a corresponding        yeast cell without the glycosyltransferase (yeast cell of        type (i) above).

Accordingly, a microorganism cell of the type (ii) above may then beused to obtain the glycosylated form of the corresponding aglycon inhigh amounts. However, it may also be used in a process to make theaglycon in higher amounts simply by e.g. first making the glycosylatedform of the aglycon, recovering it and deglycosylate it according tostandard protocols (e.g. enzymatically by use of a (β-glucosidase or byadequate chemical hydrolysis.)

Accordingly, a first aspect of the invention relates to a method ofproducing a low molecular weight organic compound comprising followingsteps:

-   -   a) fermenting a microorganism cell or a filamentous fungi cell,        which comprises a gene encoding a product involved in the        biosynthetic pathway leading to a low molecular weight organic        aglycon compound and a heterologous glycosyltransferase gene        encoding a glycosyltransferase capable of glycosylating the        produced aglycon, in a suitable medium, wherein the cell        produces the aglycon and the corresponding glycosylated form of        the aglycon; and    -   b) recovering the glycosylated form of the aglycon compound;        -   (i) wherein the low molecular weight organic aglycon            compound has a molecular weight from 50 to 3000 g/mol, and        -   (ii) wherein the glycosyltransferase is a            glycosyltransferase capable of conjugating a sugar to the            aglycon compound, wherein the sugar is a sugar selected from            the group consisting of galactose, glucosamine,            N-acetylglucosamine, xylose, glucuronic acid, rhamnose and            glucose.

A second aspect of the invention relates to a microorganism cell or afilamentous fungi cell that comprises a gene encoding a product involvedin the biosynthetic pathway leading to a low molecular weight organicaglycon compound and a heterologous glycosyltransferase gene encoding aglycosyltransferase capable of glycosylating the produced aglycon,wherein the cell, when fermented in a suitable medium, produces theaglycon and the corresponding glycosylated form of the aglycon, andwherein the glycosyltransferase is a glycosyltransferase capable ofconjugating a sugar to the aglycon compound, wherein the sugar is asugar selected from the group consisting of galactose, glucosamine,N-acetylglucosamine, xylose, glucuronic acid, rhamnose and glucose.

As said above, the basic principle behind the method described above maybe used to produce an aglycon of interest in higher yields(overproduction of the aglycon of interest).

Accordingly, a third aspect of the invention relates to a method ofproducing a low molecular weight organic aglycon compound comprisingfollowing steps:

-   -   a) growing a cell, which comprises a gene encoding a product        involved in the biosynthesis pathway leading to a low molecular        weight organic aglycon compound and a glycosyltransferase gene        encoding a glycosyltransferase capable of glycosylating the        produced aglycon, under suitable conditions wherein the cell        produces the aglycon and the associated glycosylated form of the        aglycon;    -   b) deglycosylating the glycosylated form of the aglycon; and    -   c) recovering the aglycon compound;        -   (i) wherein the low molecular weight organic aglycon            compound has a molecular weight from 50 to 3000, and        -   (ii) wherein the glycosyltransferase is a            glycosyltransferase capable of conjugating a sugar to the            aglycon compound.

An advantage of using a glycosyltransferase in a method as describedherein may further be to use the different specificities of knownglycosyltransferases. For instance, it is known that someglycosyltransferases are enantiomer specific (see e.g. Jones, P et al,J. of Biological Chemistry (1999), 274:35483-35491 and WO03/023035).Consequently, if one for instance wants to make a specific enantiomerfor e.g. an aglycon then one could choose to use such an enantiomerspecific glycosyltransferase.

A fourth aspect of the invention relates to a method for selecting acell with increased production of a glycosylated form of a low molecularweight organic aglycon compound comprising following steps:

-   -   a) growing a cell, which comprises a gene encoding a product        involved in the biosynthesis pathway leading to a low molecular        weight organic aglycon compound and a glycosyltransferase gene        encoding a glycosyltransferase capable of glycosylating the        produced aglycon, under suitable conditions wherein the cell        produces the aglycon and the corresponding glycosylated form of        the aglycon;    -   b) treating the cell in a way that changes the expression level        of at least one gene involved in the biosynthesis pathway        leading to a low molecular weight organic aglycon and/or the        glycosyltransferase gene capable of glycosylating the produced        aglycon in order to make a library of cells with different        expression levels of the genes; and    -   c) selecting a cell that produces a higher amount of the        glycosylated form of the aglycon as compared to the cell of step        a);        -   (i) wherein the low molecular weight organic aglycon            compound has a molecular weight from 50 to 3000, and        -   (ii) wherein the glycosyltransferase is a            glycosyltransferase capable of conjugating a sugar to the            aglycon compound.

Example 8 herein describes how this method is used to make anArabidopsis thaliana plant capable of producing increased mg of theglucoside dhurrin per gram of fresh weight. The starting cell of step a)is the Arabidopsis thaliana transgenic cell described in Tattersall, D Bet al, Science (2001) 293:1826-8. As explained above the Arabidopsisthaliana transgenic cell comprises the entire pathway for synthesis ofthe cyanogenic glucoside dhurrin. It was demonstrated that thetransgenic Arabidopsis thaliana plant was capable of producing 4 mg ofdhurrin per gram of fresh weight. After performing the selecting methodas described in example 8 an Arabidopsis thaliana transgenic cell isselected in step c) that produces more than 6 mg of dhurrin per gram offresh weight.

Without being limited to theory, it is believed to be the first timethat a transgenic plant has been provided that is capable of producingmore than 4 mg per gram of fresh weight of a glycosylated form of a lowmolecular weight organic aglycon compound.

Accordingly, a fifth aspect of the invention relates to a transgenicplant capable of producing more than 5 mg per gram of fresh weight of aglycosylated form of a low molecular weight organic aglycon compound,

-   -   (i) wherein the low molecular weight organic aglycon compound        has a molecular weight from 50 to 3000.

DEFINITIONS

Prior to a discussion of the detailed embodiments of the invention isprovided a definition of specific terms related to the main aspects ofthe invention.

The term “aglycon” denotes non-carbohydrate part of the correspondingglycosylated form of the aglycon. It may also be defined as an acceptorcompound capable of being conjugated to a sugar. In a number of relevantexamples, the aglycon is an alcohol with a hydroxy group suitable forbeing glycosylated. An example of this is p-hydroxymandelonitrile (seeFIG. 1) which has a hydroxy group that can be conjugated (glycosylated)with glucose to get dhurrin. (dhurrin is here the correspondingglycosylated form of the aglyconp-hydroxymandelonitrile). In thisexample, wherein the sugar is glucose the aglycon may be termedaglucone. Further, when the sugar is glucose the term glucosylated maybe used instead of glycosylated.

An aglycon may also be glycosylated at different group than a hydroxygroup, in particular at other nucleophilic groups such as a carboxylicacid, SH—, nitrogen, amine, imine or C—C group.

The term “gene encoding a product involved in the biosynthesis pathwayleading to a low molecular weight aglycon compound” should be understoodaccording to the art as a gene encoding a product involved in thebiosynthesis pathway leading to a low molecular weight aglycon compound.The gene encoded product is normally a polypeptide. However the productmay also for instance be a RNA molecule affecting the expression of agene. The encoded product of the gene may be directly involved in thebiosynthesis pathway or indirectly via e.g. other precursors orintermediated. The important issue, independently of the precisemechanism behind it, is that the gene makes it possible for the cell tosynthesize the aglycon compound of interest as described herein. The artdescribes numerous suitable examples of such genes. Just forillustration one example could be CYP71E1 from Sorghum bicolor thatstarting from p-hydroxyphenylacetonitrile is involved the biosynthesispathway leading to a low molecular weight aglycon compoundp-hydroxymandelonitrile (see FIG. 1 herein and Tattersall, D B et al,Science (2001) 293:1826-8). Further examples are the genes involved inthe biosynthesis pathway leading to a low molecular weight aglyconcompound vanillin as described in working examples herein.

The term “glycoside” denotes a compound which on hydrolysis gives asugar and a non-sugar (aglycon) residue, e.g. glucosides give glucose,galactosides give galactose.

The term “glycosyltransferase” denotes a glycosyltransferase capable ofconjugating a sugar to an aglycon as described herein. The sugar maye.g. be D and L isomers of galactose, glucosamine, N-acetylglusamine,xylose, glucuronic acid, rhamnose, arabinose, mannose or glucose.Alternatively the sugar may be a carbohydrate derivative such as e.g.inositol, D-olivose, rhodinose and etc available as nucleotidediphosphates. Further the sugar may for instance be e.g. amonosaccharide, a disaccharide or a trisaccharide. In the case of oligo-and polysaccharides the sugars are linked one by one, by e.g. involvinguse of one or several glucosyltransferases. Further, a list of suitablesugars can be seen in US2003/0130205A1 paragraphs [0029] to [0036]. Ifthe sugar is glucose the glycosyltransferase may be termed aglucosyltransferase.

The term “growing a cell” in relation to step a) of the third aspectshould be understood broadly in the sense of growing a cell undersuitable conditions (temperature, nutrients etc.) that allows growth ofthe cell. If the cell is e.g. a plant cell this means e.g. growth of theplant cell under conditions where e.g. a mature plant is obtained. Ifthe cell is a microorganism this could e.g. be fermenting of themicroorganism cell in a suitable medium where the microorganism iscapable of growing.

The term “recovering” in relation to “recovering the glycosylated formof the aglycon compound” of step b) of the first aspect of the inventionand “recovering the aglycon compound” of step c) of third aspect of theinvention should be understood broadly in the sense that the compound isrecovered from the cell or from e.g. the supernatant of the medium wherethe cell for instance is fermented in order to get the compound in ahigher purity than before the recovery step. The recovery step mayinclude more or less detailed purification steps. Preferably thecompound is at some point after the recovery step present in acomposition where the composition comprises at least 4% (w/w) of thecompound, more preferably at least 10% (w/w) of the compound, even morepreferably at least 20% (w/w) of the compound and most preferably atleast 50% (w/w) of the compound. The skilled person is aware of suitablepurification protocols (e.g. by using adequate purification columns) toobtain the desired purity. Preferably after recovering there isrecovered at least 10 mg compound, more preferably there is recovered atleast 1 g compound, even more preferably there is recovered at least 10g compound, and most preferably there is recovered at least 500 gcompound. Preferably there is recovered from 10 mg to 100 kg compound.

Embodiment(s) of the present invention is described below, by way ofexample(s) only

DRAWINGS

FIG. 1: Shows the pathway for synthesis of the tyrosine-derivedcyanogenic glucoside dhurrin (a secondary metabolite). The pathway forsynthesis included two genes involved in the biosynthesis pathway(CYP79A1 and CYP71E1) and a glucosyltransferase (sbHMNGT) capable ofglucosylating the last intermediate (p-hydroxymandelonitrile) to get theglucoside dhurrin.

DETAILED DESCRIPTION OF THE INVENTION Cell

The cell suitable to growth as specified under step a) of the method ofthe third aspect of the invention may be any suitable cell such as anyeukaryotic or prokaryotic cell. Preferably the cell is a cell selectedfrom the group consisting of a plant cell, a filamentous fungal cell anda microorganism cell.

As explained above one of the primary advantages of use of the cell asdescribed herein is that one can use it to get higher yields (getoverproduction) of the glycosylated form of the aglycon or, after asuitable step of deglycosylating the glycosylated form of the aglycon,get higher yields (get overproduction) of the aglycon.

Accordingly a preferred cell is a cell wherein the cell with theglycosyltransferase during growing is capable of producing higheramounts of the glycosylated form of the aglycon as compared to theamounts of the corresponding aglycon produced by the cell without theglycosyltransferase.

When the cell is a microorganism cell this may e.g. be expressed as,wherein the microorganism cell with the glycosyltransferase duringculture fermentation is capable of producing higher amounts of theglycosylated form of the aglycon as compared to the amounts of thecorresponding aglycon produced by the same microorganism cell withoutthe glycosyltransferase.

Preferably the cell (in particular a microorganism cell) should, when itcomprises the glycosyltransferase, produce at least 1.1 times higheramounts of the glycosylated form of the aglycon as compared to theamounts of the corresponding aglycon produced by the same microorganismcell without the glycosyltransferase, more preferably at least 1.25times higher amounts of the glycosylated form of the aglycon, even morepreferably at least 1.5 times higher amounts of the glycosylated form ofthe aglycon and most preferably at least 2 times higher amounts of theglycosylated form of the aglycon.

A main advantage of the present invention relates to this overproductionof the glycosylated form of the aglycon and the term relating to higherproduction Of the glycosylated form of the aglycon should therefore beunderstood in view of this and as generally understood by the skilledperson. Consequently, the higher amounts of the glycosylated form of theaglycon may be accumulated within the cell where it can be recoverede.g. after lysis of the cell. Alternatively, the glycosylated form ofthe aglycon may e.g. be secreted from the cell and therefore accumulatesin e.g. the culture media. The latter is particular relevant when thecell is a microorganism cell.

Plants which include a plant cell according to the invention are alsoprovided as are seeds produced by said plants.

In a preferred embodiment of the invention said plant is selected from:corn (Zea. mays), canola (Brassica napus, Brassica rapa ssp.), alfalfa(Medicago sativa), rice (Oryza sativa), rye (Secale cerale), sorghum(Sorghum bicolor, Sorghum vulgare), sunflower (helianthus annuas), wheat(Tritium aestivum and other species), Triticale, Rye (Secale) soybean(Glycine max), tobacco (Nicotiana tabacum), potato (Solanum tuberosum),peanuts (Arachis hypogaea), cotton (Gossypium hirsutum), sweet potato(Impomoea batatus), cassava (Manihot esculenta), coffee (Cofea spp.),coconut (Cocos nucifera), pineapple (Anana comosus), citrus (Citrusspp.) cocoa (Theobroma cacao), tea (Camellia senensis), banana (Musaspp.), avacado (Persea americana), fig (Ficus casica), guava (Psidiumguajava), mango (Mangifer indica), olive (Olea europaea), papaya (Caricapapaya), cashew (Anacardium occidentale), macadamia (Macadamiaintergrifolia), almond (Primus amygdalus), apple (Malus spp), Pear(Pyres spp), plum and cherry tree (Prunus spp), Ribes (currant etc.),Vitis, Jerusalem artichoke (Helianthemum spp), non-cereal grasses (Grassfamily), sugar and fodder beets (Beta vulgaris), chicory, oats, barley,vegetables, and ornamentals.

Preferably, plants of the present invention are crop plants (forexample, cereals and pulses, maize, wheat, potatoes, tapioca, rice,sorghum, millet, cassava, barley, pea, sugar beets, sugar cane, soybean,oilseed rape, sunflower and other root, tuber or seed crops. Otherimportant plants maybe fruit trees, crop trees, forest trees or plantsgrown for their use as spices or pharmaceutical products (Mentha spp,clove, Artemesia spp, Thymus spp, Lavendula spp, Allium spp., Hypericum,Catharanthus spp, Vinca spp, Papaver spp., Digitalis spp, Rawoffia spp.,Vanilla spp., Petrusilium spp., Eucalyptus, tea tree, Picea spp, Pinusspp, Abies spp, Juniperus spp., Horticultural plants to which thepresent invention may be applied may include lettuce, endive, andvegetable brassicas including cabbage, broccoli, and cauliflower,carrots, and carnations and geraniums.

The present invention may be applied in tobacco, cucurbits, carrot,strawberry, sunflower, tomato, pepper, Chrysanthemum.

Grain plants that provide seeds of interest include oil-seed plants andleguminous plants. Seeds of interest include grain seeds, such as corn,wheat, barley, nee, sorghum, rye, etc. Oil-seed plants include cottonsoybean, safflower, sunflower, Brassica, maize, alfalfa, palm, coconut,etc. Leguminous plants include beans and peas. Beans include guar,locust bean, fenugreek, soybean, garden beans, cowpea, mungbean, limabean, fava been, lentils, chickpea.

In a further preferred embodiment of the invention said plant isselected from the following group: maize, rice, wheat, sugar beet, sugarcane, tobacco, oil seed rape, potato and soybean.

The whole genome of Arabidopsis thaliana plant has been sequenced(Paquette, S. et al, Phytochemistry 62 (2003) 399-413). Consequently,very detailed knowledge is available for this plant and it may thereforebe a preferred plant cell to work with.

Accordingly, a very preferred plant cell is an Arabidopsis cell and inparticular an Arabidopsis thaliana cell.

Filamentous fungi includes all filamentous forms of the subdivisionEumycota and Oomycota (as defined by Hawksworth et al., 1995, supra).The filamentous fungi are characterized by a vegetative myceliumcomposed of chitin, cellulose, glucan, chitosan, mannan, and othercomplex polysaccharides. Vegetative growth is by hyphal elongation andcarbon catabolism is obligately aerobic. In contrast, vegetative growthby yeasts such as Saccharomyces cerevisiae is by budding of aunicellular thallus and carbon catabolism may be fermentative.

In a more preferred embodiment, the filamentous fungal cell is a cell ofa species of, but not limited to, Acremonium, Aspergillus, Fusarium,Humicola, Mucor, Myceliophthora, Neurospora, Penicillium, Thielavia,Tolypodadium, and Trichoderma or a teleomorph or synonym thereof.

A preferred microorganism cell suitable to be used in a method asdescribed herein is a microorganism cell selected from the groupconsisting of a yeast cell and prokaryotic cell.

A preferred yeast cell is a yeast cell selected from the groupconsisting of Ascomycetes, Basidiomycetes and fungi imperfecti.Preferably a yeast cell selected from the group consisting ofAscomycetes

Preferred Ascomycetes yeast cell selected from the group consisting ofAshbya, Botryoascus, Debaryomyces, Hansenula, Kluveromyces, Lipomyces,Saccharomyces spp e.g. Saccharomyces cerevisiae, Pichia spp.,Schizosaccharomyces, spp.

A preferred yeast cell is a yeast cell selected from the groupconsisting of Saccharomyces spp e.g. Saccharomyces cerevisiae, andPichia spp.

In a method as described herein a very preferred cell is a prokaryoticcell. A preferred prokaryotic cell is selected from the group consistingof Bacillus, Streptomyces, Corynebacterium, Pseudomonas, lactic acidbacteria and in particular an E. coli cell.

A preferred Bacillus cell is B. subtilis, B. amyloliquefaciens or B.licheniformis.

A preferred Streptomyces cell is S. setonii.

A preferred Corynebacterium cell is C. glutamicum.

A preferred Pseudomonas cell is P. putida or P. fluorescens

A preferred cell is a cell without active at least some of the genesencoding a beta-glycosidase that deglycosylates the glycosylated form ofthe aglycon compound of interest to be produced as described herein.Further, it is preferred that the cell comprises a permease or othertransport protein enabling the cell to release or secrete the glycosideto the medium or to an internal compartment than the one where it isglycosylated.

Transformation of suitable DNA containing vectors into the cellsdescribed above is routine work for the skilled person. Suitable vectorscan be constructed, containing appropriate regulatory sequences,including promoter sequences, terminator fragments, polyadenylationsequences, enhancer sequences, marker genes and other sequences asappropriate. For further details see, for example Sambrook et al. (1989)Molecular cloning: A laboratory manual, Cold Spring Harbor lab., ColdSpring Harbor, N.Y.; Ausubel, F. M. et al. (eds.) “Current protocols inMolecular Biology”. John Wiley and Sons, 1995; Harwood, C. R., andCutting, S. M. (eds.) “Molecular Biological Methods for Bacillus”. JohnWiley and Sons, 1990).

In relation to examples of suitable plant cell vectors and suitableplant transformation techniques reference is made to WO02/103022. Inrelation to filamentous fungi cells reference is made to EP869167.

Preferably, the cell is a cell wherein the cell expresses a heterologousglycosyltransferase gene as described herein, in particular amicroorganism cell or a filamentous fungi cell that expresses aheterologous glycosyltransferase gene as described herein.

In this connection, the term “heterologous glycosyltransferase gene”should be understood according to the art as a glycosyltransferase genethat has been introduced into a cell that, before the introduction, didnot express the glycosyltransferase gene.

Alternatively, the glycosyltransferase gene may be an endogenousglycosyltransferase gene naturally produced by the cell.

Glycosyltransferase:

As described above, the art describes a number of glycosyltransferasesthat can glycosylate a low molecular weight organic compound of interestsuch as secondary metabolites from e.g. plants and fungi. Based on DNAsequence homology of the sequenced genome of the plant Arabidopsisthaliana it is believed to contain around 100 differentglycosyltransferases. These and numerous others have been analyzed inPaquette, S. et al, Phytochemistry 62 (2003) 399-413. FIG. 1 of thisarticle is a so-called multiorganism tree providing names of numeroussuitable glycosyltransferases.

WO01/07631, WO01/40491 and (Arend, J. et al., Biotech. & Bioeng (2001)78:126-131) describe that at least some of these glycosyltransferasesare capable of glycosylating a number of different structurally relatedsecondary metabolites and other structurally related low molecularweight organic compounds.

Further, numerous suitable sequences of glycosyltransferases may befound on the Carbohydrate-Active enZYmes (CAZY) database.

In the CAZY database, there can de found suitable glycosyltransferasesequences from virtually all species including, animal, insects, plant,microorganisms.

Accordingly, the skilled person has at his disposal a number ofdifferent glycosyltransferases capable of glycosylating numerousdifferent secondary metabolites and other low molecular weight organiccompounds. This fact is described in further details below by way ofsome illustrative specific examples.

Although glucosyltransferases are generally thought to be relativelysubstrate specific it has been shown that other substrates can beprocessed at significant levels if they are presented to the enzyme. Ithas been shown that expression of the sorghum CYP79A1 in Arabidopsisresulted in the production of large amountsp-hydroxybenzylglucosinolate, which is not a naturally occurringglucosinolate (S-glucoside) of Arabidopsis (Bak et al, 2000, PlantPhysiology 123:1437-1448). The new glucosinolate is produced fromp-hydroxyphenylacetaldoxime, which is formed from tyrosine by CYP79A1and subsequently channeled into the pre-existing glucosinolatebiosynthetic pathway and to the associated glucosyltransferases.

Moreover, a glucosyl transferase, arbutin synthase, isolated from themedicinal plant Rauvolfia serpentina was shown to have considerableactivity to other substrates than the native hydroquinone (Arend et al,2001, Biotechnology and Bioengineering 76:126-131). When some of thesesubstrates, like vanillin or p-hydroxyacetophenone, were fed to culturesof E. coli that had been engineered to express the plant glucosyltransferase the substances were taken up and converted to theircorresponding glucosides, vanillin-β-D-glucoside and picein. These twoproducts, both of which are of commercial interest, were subsequentlyreleased from the bacteria.

These examples show that glucosyl transferases can act on substratesthat are normally not present in the metabolic pathway and that this canlead to the formation of novel glucosides of natural products.

As said above the skilled person has at his disposal a number ofdifferent glycosyltransferases capable of glycosylating numerousdifferent secondary metabolites and other low molecular weight organiccompounds. Further, he may by use of known routine methods easilyidentify further suitable glycosyltransferases capable of glycosylatingspecific low molecular weight organic compounds of interest. Below aregiven some examples of such suitable methods.

The numerous known DNA glycosyltransferase sequences may be used to makeappropriate PCR primers to done new glycosyltransferases. This coulde.g. be done by a method comprising following steps:

-   -   (a) preparing a cDNA library from a cell (e.g. plant tissue        cell) expressing glucosyltransferases,    -   (b) using relevant known DNA glycosyltransferase sequences to        make appropriate PCR primers to amplify part of the        glucosyltransferase cDNA from the cDNA    -   (c) using the DNA obtained in steps (b) as a probe to screen the        DNA library prepared from cell expressing glucosyltransferases,        and    -   (e) identifying and purifying vector DNA comprising an open        reading frame encoding a glucosyltransferase of interest.

Alternatively, a suitable glucosyltransferase may be identified by useof a so-called expression cloning strategy. A suitable expressioncloning strategy could be a method comprising following steps:

-   (a) preparing a cDNA library from a cell (e.g. plant tissue cell)    expressing glucosyltransferases;-   (b) introducing the cDNA library into expression cells by use of an    expressing vector that gives expression (transcription and    translation) of the cDNA in a growing expression cell of interest;-   (c) growing the cell in a medium comprising a toxic amount of a low    molecular weight organic aglycon compounds of interest (i.e. only    specific individual cells comprising an expressed    glucosyltransferase capable of glycosylating the aglycon of interest    will be able to grow);-   (d) isolating one or more of the growing cells and identify one that    expresses the glucosyltransferase of interest.

As described in Moehs, C P et al, Plant Journal (1997) 11:227-236 thisexpression cloning strategy may be done by use of a yeast cell. Theteaching of the present invention demonstrates that the glycosylatedform of the aglycon is less toxic to bacteria as compared to thecorresponding aglycon as such. Consequently, this expression cloningstrategy may be done by use of bacterial cells such as E. coli.

Accordingly, a separate aspect of the invention relates to expressioncloning method for obtaining a glucosyltransferase of interestcomprising following steps:

(a) preparing a cDNA library from a cell (e.g. plant tissue cell)expressing glucosyltransferases;(b) introducing the cDNA library into bacterial expression cells by useof an expression vector that gives expression (transcription andtranslation) of the cDNA in a growing expression cell of interest;(c) growing the cell in a medium comprising a toxic amount of a lowmolecular weight organic aglycon compounds of interest (i.e. onlyspecific individual cells comprising an expressed glucosyltransferasecapable of glycosylating the aglycon of interest will be able to grow);(d) isolating one or more of the growing cells and identify one thatexpresses the glucosyltransferase of interest.

Preferably, the bacterial expression cells of step (b) are E. colicells.

An advantage of an expression cloning strategy as described above itthat one directly gets a glucosyltransferase capable of glycosylatingthe aglycon of interest.

Preferably, the glycosyltransferase is a capable of conjugating a sugarto the aglycon compound, wherein the sugar is a sugar selected from thegroup consisting of galactose, glucosamine, N-acetylglucosamine, xylose,glucuronic acid, rhamnose, arabinose, mannose and glucose.

In a further preferred embodiment, the glycosyltransferase is aNDG-glycosyltransferase. Such glycosyltransferases have been identifiedin plants, animals, fungi, bacteria and viruses. Theseglycosyltransferases are characterized by utilization of NDP-activatedsugar moieties as the donor molecule and contain a conservedUGT-defining sequence motif near the C-terminus.

In a more preferred embodiment, the glycosyltransferase is aUDPG-glycosyltransferase (UGT). UGTs have been identified in plants,animals, fungi, bacteria and viruses. These glycosyltransferases arecharacterized by utilization of UDP-activated sugar moieties as thedonor molecule and contain a conserved UGT-defining sequence motif nearthe C-terminus. See (Paquette, S. et al, Phytochemistry 62 (2003)399-413) for further details in relation to the definition of thisUDPG-glycosyltransferase family.

Preferably, the glycosyltransferase is a glycosyltransferase thatconjugates a monosaccharide or a disaccharide sugar to an aglycon asdescribed herein. Most preferably glycosyltransferase is aglycosyltransferase that conjugates a monosaccharide sugar to an aglyconas described herein.

In a preferred embodiment, the glycosyltransferase is aglucosyltransferase.

Below are described examples of some suitable glycosyltransferases.

WO01/40491 describes cloning of a glycosyltransferase from the plantSorghum bicolor named sbHMNGT. This and the related homologousglycosyltransferases as described in WO01/40491 are capable ofglycosylating at least following low molecular weight organic aglyconcompounds (see Table 3 of WO01/40491):

Cyanohydrins

1) mandelonitrilep-hydroxymandelonitrile3) acetone cyanohydrinbenzyl derivatives4) hydroquinone5) benzyl alcohol6) p-hydroxybenzyl alcohol7) benzoic acid8) p-hydroxybenzoic acid9) p-hydroxybenzaldehyde10) gentisic acid11) caffeic acid12) 2-hydroxy cinnamic acid13) resveratrol (stilbene)14) salicylic acid15) p-hydroxymandelic acid16) vanillic acid17) vanillin18) 2-hydroxy methoxybenzylalcoholflavonoids19) quercetin (flavonol)20) cyanidin (anthocyanidin)21) biochanin A (isoflavone)22) naringenin (flavanone)23) apigenin (flavone)hexanol derivatives24) 1-hexanol25) trans hexen-1-ol26) cis hexen-1-ol27) 3-methyl hexen-1-ol28) 3-methyl hexen-1-ol29) indole acetic acid (plant hormone)30) geraniol (monterpenoid)31) tomatidine (alkaloid)32) nerol33) p-citronellol

Arend, J et al., Biotech. & Bioeng (2001) 78:126-131 describes cloningof a glycosyltransferase from the plant Rauvolfia seipentina. It iscapable of glycosylating at least following low molecular weight organicphenolic aglycon compounds (see table 1):

Hydroquinone, Vanillin, Saligerin, Resorcinol, Thymol, Phenol,Methylvanillin, p-Hydroxyacetophenone, Vanillic add, p-Methoxyphenol,3,4-Dimethoxyphenol, Coniferyl alcohol, o-Coumaric Acid, p-CoumaricAcid.

WO01/59140 describes a glycosyltransferase from the plant Arabidopsisthaliana. It is capable of glycosylating at least following lowmolecular weight organic aglycon compounds: caffeic acid, luteolin,quercitin-, catechin1-, syadinin.

WO02/103022 describes a glycosyltransferase from the plant Arabidopsisthaliana. It is capable of glycosylating at least following lowmolecular weight organic aglycon compounds: Benzoate substrates, inparticular p-hydroxybenzoic acid.

WO03/02035: describes a glycosyltransferase from the plant Arabidopsisthaliana. It is capable of glycosylating at least following lowmolecular weight organic aglycon phytohormone compound: Abscisic acid.

Below are described suitable assays to measure the activity of aglycosyltransferase of interest. 15 The assays are described for aglucosyltransferase. However when sugar is not glucose, one just has touse the adequate sugar (e.g. galactose) in stead of the glucose.

The ability of a glucosyltransferase to conjugate an aglycon of interestto glucose can for example be determined in an assay comprising thefollowing steps.

a) Incubation of a reaction mixture comprising ¹⁴C_UPD-glucose, aglyconand UDPglucose:aglycon-glucosyltransferase at 30° C. between 2 minutesand 2 hoursb) terminating the reaction, andc) chemical identification and quantification of the glucoside produced.

Typically the reaction mixture has a volume of 5 to 2000 μl butpreferably 20 μl and includes 10-200 mM TrisHCI (pH 7.9); μM¹⁴4C-UDP-glucose (about 11.0 GBq mmol-1); 0-300 μM UDP-glucose; 0-20 mMaglycone; 25 mM γ-gluconolactone; 0-2 μg/μl BSA and 0-10 ng/μlUDP-glucose:aglycon-glucosyltransferase. β glucosidase inhibitors otherthan y-γ-gluconolactone and protein stabilizers other than BSA may beincluded as appropriate. One possibility to terminate the reaction is toacidify the reaction mixture for example by adding 1/10 volume of 10%acetic acid.

Chemical identification and quantification of the glucoside formed inthe reaction mixture may be achieved using a variety of methodologiesincluding NHR spectroscopy, TLC analysis, HPLC analyses or GLC analysisin proper combinations with mass spectrometric analysis of theglucoside.

Reaction mixtures for analysis by NIVIR. spectroscopy usually have atotal volume of 0.5-1 ml, are incubated for 2 hours and include 0-10 mMaglycon, e.g. 2 mM p-hydroxy-mandelonitrile or 6.5 mM geraniol, 3 mMUDP-glucose, 2.5 μg gluceryltransferease, and 0.5 mg BSA. Glucosides areextracted for example with ethyl acetate and lyophillized prior to NMRanalysis.

For TLC analysis the reaction mixtures are applied to Silica Gel 60 F254plates (Merck), dried and eluted in a solvent such as ethylacetate:acetone:dichloromethane:methanol H₂O (40:30:12:10:8, v/v).Plates are dried for one hour at room temperature and exposed to storagephosphor imaging plates prior to scanning on a PhosphorImager. Based onthe specific radioactivity of the radiolabelled UDIP-glucose, the amountof glucoside formed is quantified. The radioactivity may also bedetermined by liquid scintillation counting (LSC analysis). In somecases, where the glucoside formed is derived from a very hydrophobicaglycon, e.g. mandelonitrile, the glucoside can be extracted into anethyl acetate phase and thereby be separated from unincorporated¹⁴C-UDP-glucose. 2 ml of scintillation cocktail are added to 250 IA ofeach ethyl acetate extract and analyzed using a liquid scintillationcounter. During column fractionation, those fractions containinggluceryltransferase activity can be identified using the aglyconsubstrate of interest and ethyl acetate extraction of the glucosideformed.

A glycosyltransferase gene as described herein may be introduced into acell in order to make a cell wherein the cell expresses a heterologousglycosyltransferase gene as described herein, in particular amicroorganism cell or a filamentous fungi cell that expresses aheterologous glycosyltransferase gene as described herein.

Alternatively, the glycosyltransferase gene may be an endogenousglycosyltransferase gene 30 naturally produced by the cell.

In addition genes giving raise to increased expression of theglycosyltransferase or increased yield of the glycoside may beintroduced, such genes may encode regulatory proteins, proteaseinhibitors, repressors of protease gene, genes increasing the level orprecursors, especially the relevant NDP-sugars, genes involved inNDP-metabolism, permeases and other transporters, genes reducing themetabolism of the aglycone etc.

A Gene Involved in the Biosynthesis Pathway

As said above, the term a “gene encoding a product involved in thebiosynthesis pathway leading to a low molecular weight aglycon compound”should be understood according to the art as a gene encoding a productinvolved in the biosynthesis pathway leading to a low molecular weightaglycon compound.

The art describes numerous suitable examples of such genes and thenumbers are exponentially increasing since a number of whole genomes ofdifferent plant and microorganisms are continuously published.

Reference may for example be made to the textbook “Biochemistry &Molecular Biology of Plants”, edited by Bob B. Buchanan et al, ISBN0-943088-37-2. Chapter 24: “Natural Product (Secondary Metabolites)”describes examples of a number of different suitable genes involved inthe biosynthesis pathway leading to a low molecular weight aglyconcompound.

Just for illustration one example could be CYP71E1 from Sorghum bicolorthat starting from p-hydroxyphenylacetonitrile is involved thebiosynthesis pathway leading to a low molecular weight aglycon compoundp-hydroxymandelonitrile (see FIG. 1 and Tattersall, D B et al, Science(2001) 293:1826-8).

Further examples are the genes involved in the biosynthesis pathwayleading to a low molecular weight aglycon compound vanillin as describedin working examples herein. Even further examples are given in Szczebaraet al., Nature Biotechnology (2003), 21:143-149. This article describesa recombinant yeast cell capable of producing hydrocortisone from asimple carbon source. The yeast cell comprised eight recombinantlyintroduced genes involved in the biosynthesis pathway.

As said above the skilled person has at his disposal a number ofdifferent biosynthesis pathway genes. Further, he may by use of knownroutine methods easily identify further suitable biosynthesis pathwaygenes. For instance, the numerous biosynthesis pathway gene sequencesmay be used to make appropriate PCR primers to done new suitablebiosynthesis pathway genes. This could e.g. be done by a methodcomprising following steps:

(a) preparing a cDNA library from a cell (e.g. plant tissue cell)expressing biosynthesis pathway genes of interest,(b) using relevant known biosynthesis pathway gene sequences to makeappropriate PCR primers at to amplify part of the biosynthesis pathwaygene encoding cDNA from the cDNA library,(c) using the DNA obtained in steps (b) as a probe to screen the DNAlibrary prepared from cell expressing the biosynthesis pathway genes ofinterest, and(e) identifying and purifying vector DNA comprising an open readingframe encoding a biosynthesis pathway gene of interest.

As explained above a cell used in a method as described herein comprisesa gene encoding a product involved in the biosynthesis pathway. The cellmay comprise more than one gene encoding a product involved in thebiosynthesis pathway.

A suitable example is the transgenic Arabidopsis thaliana cell describedin Tattersall, D B et al, Science (2001) 293:1826-8. It comprises thetwo biosynthesis pathway genes CYP79A1 and CYP71E1 and can thereforemake aglycon compound p-hydroxymandelonitrile from tyrosine (see FIG. 1herein).

A further example is the E coil cell described in working examplesherein that comprises sufficient biosynthesis pathway genes to make theaglycon vanillin from glucose.

A gene encoding a product involved in the biosynthesis pathway asdescribed herein may be introduced into a cell in order to make a cellwherein the cell expresses a heterologous gene encoding a productinvolved in the biosynthesis pathway as described herein, in particulara microorganism cell or a filamentous fungi cell that expresses aheterologous gene encoding a product involved in the biosynthesispathway as described herein.

Alternatively, the gene encoding a product involved in the biosynthesispathway may be an endogenous gene naturally produced by the cell.

Low Molecular Weight Organic Aglycon Compound

As said above, the low molecular weight organic aglycon compound, asdescribed herein, has a molecular weight from 50 to 3000. Preferably,the low molecular weight organic aglycon compound has a molecular weightfrom 50 to 2000, more preferably a molecular weight from 50 to 1000, andeven more preferably a molecular weight from 50 to 750. The molecularweight is the mass of one molecule in atomic mass units.

Further, the low molecular weight organic aglycon compound is preferablya compound selected from the group consisting of more or less saturatedAlkyl-, Cycloalkyl-, Cycloalkylalkyl-, Arallyl- and Aryl, with 1 to 50C-atoms and 0 to 20 heteroatoms and optionally substituted, inparticular with Hydroxy-, Amino-, Sulfide-, Carboxy-, or Nitro groups,at the 1 to 56 C-atoms and/or 0 to 20 Heteroatoms; more preferably acompound selected from the group consisting of more or less saturatedAlkyl-, Cycloalkyl-, Cycloalkylalkyl-, Arallyl- and Aryl, with 1 to 32C-atoms and 0 to 10 heteroatoms and optionally substituted, inparticular with Hydroxy-, Amino-, Sulfide-, Carboxy-, or Nitro groups,at the 1 to 32 C-atoms and/or 0 to 10 Heteroatoms.

In a preferred embodiment, the low molecular weight organic aglyconcompound is an alcohol, in particular an aromatic alcohol. An alcoholshould herein be understood in relation to the technical objective ofglycosylating the aglycon. Accordingly an aglycon defined as an alcoholis herein a compound that contains a hydroxyl- (—OH) functional groupthat can be glycosylated by use of a glycosyltransferase as describedherein. A non limiting example of a preferred aglycon compound which isan aromatic alcohol is vanillin or p-hydroxymandelonitrile.

Alcohols also include e.g. some ketones, aldehydes and other compoundsbeing in equilibrium with an alcohol, e.g. enols, furanosider,pyranosider, lactames and lactones etc.

In line of above, a preferred organic aglycon compound is an organicaglycon compound that comprises a compound that contains Hydroxy-,Amino-, Imino-, Thiol-Sulfite, Sulfate, Phosphate or Phosphonate orCarboxy functional group that can be glycosylated by use of aglycosyltransferase as described herein. It may also be correspondingboron and selenium groups and compounds containing group being inequilibrium with the mentioned groups. Aglycons that comprises ahydroxyl-group is discussed immediately above.

In a preferred embodiment the organic aglycon compound is an organicaglycon compound that comprises a compound that contains a carboxyfunctional group that can be glycosylated by use of aglycosyltransferase as described herein to form an ester glycoside. Anon limiting example of such aglycon compounds is vanillic acid orp-hydroxybenzoic acid.

In a preferred embodiment the low molecular weight organic aglyconcompound is a pharmaceutical compound or a chemical intermediate of apharmaceutical compound. A suitable pharmaceutical compound may bepharmaceutical compound produced naturally in an animal, a plant, afilamentous fungi or a microorganism.

A preferred pharmaceutical compound is a pharmaceutical compoundselected from the list consisting of budesonide, raloxifine, tamoxifine,dopamine, steroids.

Further a description of suitable preferred pharmaceutical compounds canbe found in US2003/0130205A1 and US2003/0119761A1.

In a preferred embodiment the low molecular weight organic aglyconcompound is an aglycon compound selected from the list consisting ofvitamin, amino acids, fatty acids, oligopeptide, oligosaccharide,oligonucleotide, PNA, LNA, and functional equivalents thereof. For thisgroup of aglycon compounds the size of the compounds may have a biggermolecular weight than 3000. Plants may be seen as the organic chemistsper excellence in nature. More than 200.000 different natural productsare known from plants. These enable plants to deter herbivores andpests, attract pollinators, communicate with other plants and constantlyadapt to climatic changes. As explained before the majority of thesecompounds may be termed secondary metabolites.

The term “secondary metabolite” relates to that plants and microbessynthesize a large number of natural substances, in particular secondarymetabolites, with diverse and generally unclear function. In contrast tothe primary metabolites (eg amino acids, sugars, fatty acids), which areinvolved in fundamental functions like metabolism, growth, maintenanceand survival, secondary metabolites are not required for fundamentalfunctions. The term secondary metabolite should herein be understood inview of such, according to the art, standard description of the term. Ina preferred embodiment the low molecular weight organic aglycon compoundis a secondary metabolite compound, preferably a plant secondarymetabolite compound.

Examples of preferred secondary metabolite compound classes are:

-   -   Terpenoids    -   Alkaloids    -   Phenylpropanoids    -   Phenyl derivatives    -   Hexanol derivatives    -   Flavonoids    -   Coumarins, stilbenes    -   Cyanohydrins    -   Glucosinolates    -   Sterols    -   Saponin aglycones    -   Steroids    -   Hormones    -   Antibiotics    -   and Herbicides.

Of the list above, the more preferred secondary metabolite compoundclasses are:

-   -   Terpenoids    -   Alkaloids    -   Phenylpropanoids    -   Phenyl derivatives    -   Hexanol derivatives    -   Flavonoids    -   Coumarins, stilbenes    -   Cyanohydrins    -   and Glucosinolates.

Examples of preferred individual low molecular weight organic aglyconcompounds is a compound selected from the list consisting of:

mandelonitrile, p-hydroxymandelonitrile, acetone cyanohydrin,hydroquinone, benzyl alcohol, p-hydroxybenzyl alcohol, benzoic acid,p-hydroxybenzoic acid, p-hydroxybenzaldehyde, gentisic acid, caffeicacid, 2-hydroxy cinnamic acid, resveratrol (stilbene), salicylic acid,p-hydroxymandelic acid, vanillic acid, vanillin, 2-hydroxymethoxybenzylalcohol, quercetin, cyanidin (anthocyanidin), biochanin A(isoflavone), =ingrain (flavanone), apigenin (flavone), 1-hexanol, transhexen-1-ol, cis hexen-1-ol, 3-methyl hexen-1-ol, 3-methyl hexen-1-ol,indole acetic acid (plant hormone), geraniol (monoterpenoid), tomatidine(alkaloid), neral, p-citronellol, saligerin, resorcinol, thymol, phenol,methylvanillin, p-hydroxyacetophenone, p-methoxyphenol,3,4-dimethoxyphenol, coniferyl alcohol, o-coumaric acid, p-coumaricacid, caffeic acid, luteolin, quercitin-, catechin1-, cyadinin,p-hydroxybenzoic acid, abscisic acid (phytohormone),2,4,5-trichlorophenol (TCP), pentachlorophenol, 4-nitrophenol,3,5-dibromo4-hydrobenzoic acid, tetracycline, protocatechuic acid,2-phenylethanol and 2,2-bis-(4-chlorophenyl)-acetic acid.

Growing a Cell

In a method as described herein, the cell should be grown underconditions where it produces the aglycon and the correspondingglycosylated form of the aglycon. An important point in relation to thegrowth of the cell is that adequate intermediate compounds must beavailable to the cell. This means for example that if the cell is e.g.an E. coli cell comprising adequate genes involved in the biosynthesispathway leading e.g. to the aglycon compound vanillin from e.g. glucose,then the E. coli cell should be fermented under conditions where glucoseis available to the cell.

If the cell is e.g. a plant cell comprising adequate genes involved inthe biosynthesis pathway leading to the aglycon compound from e.g.tyrosine then the plant cell should be grown under conditions wheresuitable amount of tyrosine is present to the growing plant.

The skilled person knows how to grow a specific cell of interest toensure this.

A Method of Producing a Low Molecular Weight Organic Aglycon Compound

As described above the third aspect of the invention relates to a methodof producing a low molecular weight organic aglycon compound comprisingfollowing steps:

-   -   a) growing a cell, which comprises a gene encoding a product        involved in the biosynthesis pathway leading to a low molecular        weight organic aglycon compound and a glycosyltransferase gene        encoding a glycosyltransferase capable of glycosylating the        produced aglycon, under suitable conditions wherein the cell        produces the aglycon and the associated glycosylated form of the        aglycon;    -   b) deglycosylating the glycosylated form of the aglycon; and    -   c) recovering the aglycon compound;        -   (i) wherein the low molecular weight organic aglycon            compound has a molecular weight from 50 to 3000, and        -   (ii) wherein the glycosyltransferase is a            glycosyltransferase capable of conjugating a sugar to the            aglycon compound.

All embodiments above are also embodiments of this third aspect. Anessential step of this method is the deglycosylating step b). This stepis further described below, where some non-limiting examples areincluded to illustrate a number of technical advantages in relation tothis deglycosylating step. Though glucosides are often desirable naturalproducts and attempts to use transgenic glucosyl transferases to producethem have been taken (e.g. Arend et al, 2001, Biotechnology andBioengineering 76: 126-131) the corresponding aglucone can be morecommercially interesting. One example is vanillin, a natural flavour ofsignificant commercial interest. Vanillin is a phenolic compound thataccumulates in the fruits of the orchid Vanilla sp. in a glucosylatedform, gluco-vanillin. In order to obtain the desired natural flavour,gluco-vanillin must be deglucosylated.

This is achieved by fermentation (curing) of the fruits, so-calledvanilla beans, whereby endogenous beta-glucosidases are activated.

In the step b) of the method of the third aspect of the invention, theglycosylated intermediate of the desired natural product is subjected toa deglycosylating step. This may be done by chemical hydrolysisaccording to known methods in the art or enzymatically by e.g. use anenzyme with beta-glycosidase activity. Numerous suitablebeta-glycosidases are known to the skilled person. This can e.g. beachieved first by recovering glycosylated form of the aglycon forinstance by extracting the glucosylated intermediate in a suitablesolvent, e.g. methanol, or by collecting it after excretion from theproducing organism or plant. Secondly, the glucosylated intermediate ispurified and exposed to a beta-glucosidase in vitro or to an adequatechemical hydrolysis.

Alternatively, the stabilized glucosylated intermediate can be let alonein the plant and be allowed to accumulate in cellular compartments ortissues where it is protected from endogenous beta-glucosidase activity.In such a protected spatial environment the glucosylated intermediate isno longer exposed to enzymatic activity that could further metabolizeits deglucosylated equivalent.

The glycoside may also be modified e.g. by acetylation or othermodifications and in that way be protected from glycosidases. It could,however, also be protected in time, if the desired natural product waskept in its glucosylated form until developmental changes in the planthad led to a significant decrease in the activity of the enzymes thatcould otherwise metabolize its deglucosylated form.

It is preferred for the present invention that glycosylation of thedesired aglycon is uncoupled from its subsequent deglycosylation, sincethe aglycon would otherwise be subject to further metabolic processing.As indicated above, this uncoupling can be either in time or space.Preferably it is in space.

In the final step c) of the method of the third aspect of invention, thedesired aglycon is recovered.

The present method will address at least three problems related tobiotechnological production of organic molecules. First, it will allowfor increased production of organic molecules that are stable andconstitute the final product of the respective biosynthetic pathway ofthe production organism. Second, it will allow for increased yield oforganic molecules that are not the end product of the respectivebiosynthetic pathway and are consequently further metabolized by theproduction organism Third, it will allow for increased production oforganic molecules that are toxic to the production organism.

Regarding toxicity is show in examples 1 and 2 that the presence of aheterologous UDPG-glucosyltransferase in a microorganism can increaseits tolerance to vanillin through glucosylation. This principle isevidently not limited to vanillin but can be applied to any toxicsubstance that can be converted into a less toxic glucoside by theheterologous UDPG-glucosyltransferase, including e.g. taxol.

This approach can be helpful in increasing tolerance to a desiredorganic molecule, which is the end product of its biosynthetic pathwayand is therefore accumulated in the production organism toconcentrations that might be limiting production. However, the approachmight also address detoxification of substances that are structurally orbiosynthetically unrelated to the desired molecule. Such substancescould be byproducts of the desired biosynthetic pathway or contaminantsin the growth medium.

In the industrial fermentation of ethanol from lignocellulose, vanillinhas been reported to be one of the strongest inhibitors among thehydrolysis byproducts (Delgenes et al, 1996, Enzyme Microb Technol, 19:220) and it acts as a strong growth inhibitor at concentrations of 5 elin the medium (Pfeifer et al, 1984, Biotechnol Lett 6: 541).Accordingly, fermentation of lignocellulose using microorganismsexpressing a heterologous UDPG-glucosyltransferase might not onlyincrease the yield of ethanol but could potentially also lead to a meansfor parallel production of commercially valuable vanillin after recoveryand deglucosylation of non-toxic vanillin glucoside.

The method as described herein are of direct importance tobiotechnological production of several organic molecules, since it canincrease yield of organic molecules that are stable and constitute thefinal product of the respective biosynthetic pathway of the productionorganism. The feasibility of this approach is shown in examples 3 and 4using production of vanillin in a microbial system as an example.However, it is obvious for those skilled in the art that this principleis not limited to production of vanillin from ferulic acid, but can beapplied in virtually any biosynthetic pathway where the desired organicmolecule is the end product and opposes at least some inhibition toproduction.

When the desired organic molecule is the end product of its biosyntheticpathway it will itself in many cases be a limiting factor in the rate ofproduction. This is due to product inhibition of enzymes in thebiosynthetic pathway and thus leads to reduced production rate. Insteadof achieving high levels of the desired end product, an intermediateproduct might build up and either accumulate or be directed into othermetabolic pathways and consequently become lost for the desiredbiosynthetic pathway.

The method will overcome this product inhibition by adding an additionalstep to the biosynthetic pathway, so the inhibiting product is removedand thereby is no longer able to inhibit the enzyme. When biosynthesisis no longer suppressed by product inhibition the turnover of theinitial substrates and their conversion into first the desired productand subsequently into its glucosylated derivative will substantiallyincrease. According to the method, the glucosylated derivative is thenextracted and converted back into the desired aglucone by e.g.beta-glucosidase activity.

The desired organic molecule might, however, not always be the endproduct of its biosynthetic pathway in the production organism. In suchcases, it is further metabolized and might eventually be lost forcommercial recovery. In examples 5 and 6 is demonstrated how the methodcan be applied to rescue such intermediates. In the examples, analdehyde oxime is rescued by glucosylation of a heterologousUDPG-glucosyltransferase, but it is evident for those skilled in the artthat the principle is general and can be used for any intermediateproduct of desire that can be glucosylated. The examples address amolecule of desire, the oxime aldehyde, which is not naturally producedin the production organism, but in other examples the organic moleculeof desire might as well be a substance that is produced naturally.

The sorghum cytochrome P450 enzyme complex CYP79 catalyses theconversion of the amino acid tyrosine into an aldehyde oxime,p-hydroxyphenylacetaldoxime (Bak et al, 2000, Plant Physiol 123: 1437).Attempts to transfer the sorghum CYP79 gene to other plants ormicroorganisms leads to very low production of the oxime, since it istoxic and is being further metabolised to at least two presentlyunidentified substances, X and Y, that might be nitrile and alcoholderivates (Halkier al, 1995, Arch Biochem Biophys 322: 369; Bak et al,2000, Plant Physiol 123: 1437). In plants, e.g. tobacco and Arabidopsis,the oxime is also glucosylated into p-hydroxyphenyl-(acetaldoximeglucoside) by an oxime specific UDPG-glucosyl transferase.

It is a general principle of the method that a glucosylated form of thedesired organic molecule becomes the final product produced in theproduction organism. In addition to the advantages this principle canhave in yield, it might also posses some benefits during purification orextraction of the desired organic molecule. This is demonstrated inexample 7, where it is exploited that the solubility of the desiredmolecule changes after glucosylation.

This principle can be useful if the desired molecule is difficult toseparate from other substances present in the production organism or thegrowth medium. The glucosylated form could e.g. be exported to anothercompartment than the contaminating molecule, thereby facilitatingpurification. Alternatively, it could be excreted to the growth medium,whereas the contaminating molecule is left alone within the organism.Moreover, the purification process could utilize that the glucosylatedform of the desired molecule has novel chemical properties, includingnot only solubility but also chromatographic properties etc.

Method to Selecting Transgenic Organisms with Increased BiosynthesisFlow

In example 6, is shown an example of how the method of the third aspectof the invention can be utilized to establish commercial production ofp-hydroxyphenylacetaldoxime in microorganisms. This is achieved bytransferring both the sorghum CYP79 gene and the oxime specificUDPG-glucosyltransferase (see FIG. 1) into the microorganism. Thisresults in the production of p-hydroxyphenyl-(acetaldwdme glucoside),which is stable and non-toxic. Moreover, this glucoside can be extractedand converted into the desired p-hydroxyphenylacetaldoxime by e.g. invitro beta-glucosidase activity.

Using this approach, the method not only makes the production of thedesired molecule, the oxime, possible. It also allows for the selectionof transgenic microorganisms with high expression levels of the sorghumCYP79 in a very active form, since the toxic product of the enzyme isreadily detoxified by glucosylation. If the oxime specific UDPG-glucosyltransferase was not present, natural selection would favormicroorganisms harboring the CYP79 gene in a low expressing state and ina mutated form with less activity.

The example discussed above, illustrates how the method can be utilizedto obtain, through selection, more efficient production organisms. Thisprinciple is not restricted to the example above, but will obviouslyapply for many other biosynthetic pathways and production organisms.

Accordingly, as said above a fourth aspect of the invention relates to amethod for selecting a cell with increased production of a glycosylatedform of a low molecular weight organic aglycon compound comprisingfollowing steps:

-   -   a) growing a cell, which comprises a gene encoding a product        involved in the biosynthesis pathway leading to a low molecular        weight organic aglycon compound and a glycosyltransferase gene        encoding a glycosyltransferase capable of glycosylating the        produced aglycon, under suitable conditions wherein the cell        produces the aglycon and the corresponding glycosylated form of        the aglycon;    -   b) treating the cell in a way that changes the expression level        of at least one gene involved in the biosynthesis pathway        leading to a low molecular weight organic aglycon and/or the        glycosyltransferase gene capable of glycosylating the produced        aglycon in order to make a library of cells with different        expression levels of the genes; and    -   c) selecting a cell that produces a higher amount of the        glycosylated form of the aglycon as compared to the cell of step        a);        -   (i) wherein the low molecular weight organic aglycon            compound has a molecular weight from 50 to 3000, and        -   (ii) wherein the glycosyltransferase is a            glycosyltransferase capable of conjugating a sugar to the            aglycon compound.

The term “library of cells” may herein also be termed “population ofcells”. The library of cells may comprise as little as two differentcells.

The term “different expression levels of the genes” may be a librarycomprising individual cells with both increased or decreased expressionlevels of the genes. Preferably, the library mainly comprises individualcells with increased expression levels of the genes.

Wherein the cell is within a plant the library will comprise a libraryof different plants. Preferably the library comprises 10² plants, morepreferably 10³ plants, even more preferably 10⁵ plants, even morepreferably 10⁶ plants.

When the cell is a microorganism the library may normally easily be maderelatively bigger. Consequently, when the cell is a microorganism thelibrary comprises 10⁵ cells, more preferably 10⁷ cells, even morepreferably 10⁸ cells, even more preferably 10⁹ cells.

The selected cell of this method may be a preferred cell to use in amethod of producing a low molecular weight organic compound of the firstaspect of the invention or a method of producing a low molecular weightorganic aglycon compound of the third aspect of the inventions or inrelation to the different embodiments of these methods to make a lowmolecular weight organic compound.

Accordingly, an embodiment of the invention relates to a method wherethere is first selected a cell as described in the fourth aspect aboveand thereafter this cell is used in a method of producing a lowmolecular weight organic compound of the first aspect of the inventionor a method of producing a low molecular weight organic aglycon compoundof the third aspect of the inventions or in relation to the differentembodiments of these methods to make a low molecular weight organiccompound.

The treating of the cell step b) above may be done by numerous differentstrategies known to the skilled person. Examples are mutagenesis such asUV treatment, adequate chemical treatment to make DNA mutations, randommutagenesis of e.g. specific promoters of the relevant genes, shufflingof cells to make a library of shuffled cells and etc.

The selected cell of step c) should preferably produce 1.25 times higheramounts of the glycosylated form of the aglycon as compared to the cellof step a), more preferably the selected cell of step c) shouldpreferably produce 1.5 times higher amounts of the glycosylated form ofthe aglycon as compared to the cell of step a), even more preferably theselected cell of step c) should preferably produce 2 times higheramounts of the glycosylated form of the aglycon as compared to the cellof step a), and most preferably the selected cell of step c) shouldpreferably produce 3 times higher amounts of the glycosylated form ofthe aglycon as compared to the cell of step a).

The selecting may be done in a number of ways according to the art. Forinstance in a micro titer assay where each well comprises a sample of aspecific cell and there is measured amounts of the glycosylated form ofthe aglycon. There are numerous other ways of doing this according tothe general knowledge of the skilled person.

Example 8 describes how this method is used to make an Arabidopsisthaliana plant capable of producing increased mg of dhurrin per gram offresh weight. The starting cell of step a) is the Arabidopsis thalianatransgenic cell described in Tattersall, D B et al, Science (2001)293:18268. As explained above the Arabidopsis thaliana transgenic cellcomprises the entire pathway for synthesis of the cyanogenic glucosidedhurrin. It was demonstrated that the transgenic Arabidopsis thalianaplant was capable of producing 4 mg of dhurrin per gram of fresh weight.After performing the method as described in example 8 an Arabidopsisthaliana transgenic cell is selected in step c) that produces more than6 mg of dhurrin per gram of fresh weight.

Without being limited to theory, it is believed to be the first timethat a plant has been provided that is capable of producing more than 4mg per gram of fresh weight of a glycosylated form of a low molecularweight organic aglycon compound.

Accordingly, as said above a fifth aspect of the invention relates to aplant capable of producing more than 5 mg per gram of fresh weight of aglycosylated form of a low molecular weight organic aglycon compound,

-   -   (i) wherein the low molecular weight organic aglycon compound        has a molecular weight from 50 to 3000.

Preferably, the plant is capable of producing more than 6 mg per gram offresh weight of a glycosylated form of a low molecular weight organicaglycon compound, more preferably the plant is capable of producing morethan 8 mg per gram of fresh weight of a glycosylated form of a lowmolecular weight organic aglycon compound. Preferably, the plantproduces from 5 mg to 40 mg per gram of fresh weight of a glycosylatedform of a low molecular weight organic aglycon compound.

Preferably, the plant is a transgenic plant.

EXAMPLES General Molecular Biology Methods

Unless otherwise mentioned the DNA manipulations and transformationswere performed using standard methods of molecular biology (Sambrook etal. (1989) Molecular cloning A laboratory manual, Cold Spring Harborlab., Cold Spring Harbor, N.Y.; Ausubel, F. M. et al. (eds.) “Currentprotocols in Molecular Biology”. John Wiley and Sons, 1995; Harwood, C.R., and Cutting, S. M. (eds.) “Molecular Biological Methods forBacillus”. John Wiley and Sons, 1990). Enzymes for DNA manipulationswere used according to the specifications of the suppliers.

Example 1 Analysis of Increased Tolerance to Vanillin in MicroorganismsExpressing a UDPG-Glucosyl Transferase

Vanillin sensitivity is determined in a number of microorganisms. Themicroorganisms includes the Escherichia coli strains DH5-alpha, TOP10,JM109 and KO1418; the Pseudomonas fluorescens strains DSM 50091, DSM50108 and DSM 50124; the Bacillus subtilis strain DSM 704; and theCorynebacterium glutamicum strain DSM 20300. The microorganisms alsoinclude strains of Saccharomyces cervisiae, S. uvarum, S. bayanus, S.paradoxus, S. kudriavzevii, S. mikatae, S. cadocanus, S. seivazzii, S.castellii, S. kluyverii, Kluyveromyces lactis, Zygosaccharomycesfermentatii, Torulaspora delbruekii Debaromyces odentalis andSchizosaccharomyces pombe.

The minimum inhibitory concentration of vanillin is determined by thetwo-fold serial dilution assay (Hufford et al, 1975, J Pharm Sci 4:789). Furthermore, the concentration of vanillin necessary to inhibitgrowth by more than 50% is determined. Once the sensitivity of vanillinhas been determined in the various bacterial and yeast strains a few ofthese are selected in order to obtain microbial strains displaying abroad range of vanillin sensitivity.

The selected strains are transformed with a UDPG-glucosyl transferasegene, e.g. Sorghum bicolor UDPG-glucosyl transferase UGT85B1 (Jones etal, 1999, J Biol Chem 274: 35483), Arabidopsis thaliana UDPG-glucosyltransferase UGT89B1 (Lim et al, 2002, J Biol Chem 277: 586) andRauvolfia serpentina arbutin synthase (Arend et al, 2001, BiotechnolBioeng 76:126).

For expression of UDPG-glucosyl transferase in E. coli, theIPTG-inducible expression vectors pSP19g1OL, pKK223-3 and pET101D/Topoare employed. In addition, the newly constructed E. coli expressionvectors using constitutive E. coli glycolytic gene promoters are used.For expression in P. fluorescens, the BHR expression vector pYanni3 areused. For expression of UDPG-glucosyl transferase in yeast, the genesare PCR amplified and inserted into plasmid pJH259, in which the genesare expressed from the constitutive and strong glycolytic TPI1 promoter.Alternatively, the TPI1 promoter is exchanged with a PCR-amplified MET25promoter, which is repressible by methionine.

The UDPG-glucosyl transferase expressing microorganisms are subjected toanalysis of their sensitivity to vanillin in the growth medium asdescribed above. An increased tolerance to vanillin, determined as anincrease in either the minimum inhibitory concentration or theconcentration necessary to inhibit growth by more than 50%, means thattransgenic UDPG glucosyl transferase activity has converted some or mostof the applied vanillin into vanillin glucoside, which is considerablyless toxic.

Example 2 Identification of Glucosides in Microorganisms Expressing aUDPG-Glucosyl Transferase

Microorganisms expressing a heterologous UDPG-glucosyl transferase aregrown in medium containing appropriate levels of vanillin orethylvanillin. The microorganisms are harvested and their content ofglucosides is extracted in methanol or other suitable solvents. Thepresence of vanillin glucoside or ethylvanillin glucoside will beestablished and their levels will be quantified. The content of vanillinglucoside and ethylvanillin glucoside are compared in transgenic andnon-transgenic microorganisms as well as in microorganisms grown inmedium with and without vanillin or ethylvanillin.

The presence of increased amounts of vanillin glucoside or ethylvanillinglucoside in UDPG-glucosyl transferase expressing microorganisms grownin medium containing vanillin or ethylvanillin indicates that theaglucones are taken up and glucosylated by the transgenic organism.

Example 3 Increased Uptake and Turnover Offerulic Acid in MicroorganismsExpressing a UDPG-Glucosyl Transferase

Microorganisms capable of converting ferulic acid into vanillin aregenetically modified to express a heterologous UDPG-glucosyltransferase. Streptomyces setonii strain ATCC 39116 is used for thesestudies since it has previously been employed for industrial productionof vanillin from ferulic acid (Muheim & Lerch, 1999, Appl MicrobiolBiotechnol 51: 456; Muheim et al, 1998, EP 0885968A1). Alternatively,Pseudomonas putida strain AN103 (Narbad & Gasson, 1998, Microbiol 144:1397; Narbad et al, 1997, WO 97/35999), or Amycolatopsis sp. HR167(Rabenhorst & Hopp, 1997, EP 0761817A2) are used. The microorganisms aretransformed with the appropriate construct so as to express Sorghumbicolor UDPG-glucosyl transferase UGT85B1, Arabidopsis thalianaUDPG-glucosyl transferase UGT89B1 or Rauvolfia serpentina arbutinsynthase

The genetically modified microorganisms are grown in medium containingappropriate concentrations of ferulic acid. The uptake of ferulic acidis determined by following its concentration in the medium and itsmetabolic turnover are determined by analysis of the concentration ofvanillin and vanillin glucoside in the microorganisms and the growthmedium. These values are compared to similar analysis from experimentscarried out with non-transgenic microorganisms.

An increased uptake of ferullic acid by microorganisms expressingheterologous UDPG-glucosyl transferase and their accumulation ofvanillin glucoside demonstrate that the glucosyl transferase hasincreased the conversion of ferulic acid into vanillin, which is thensubsequently converted into vanillin glucoside.

Example 4 Increased Yield of Vanillin Through Deglucosylation ofVanillin Glucoside Produced in Microorganisms Expressing a UDPG-GlucosylTransferase

Microorganisms capable of converting ferulic acid into vanillin aretransformed with a gene encoding a UDPG-glucosyl transferase and aregrown in the presence of ferulic acid. The concentration of ferulic acidin the growth medium is monitored and kept at constant level in order tocompensate for the amount taken up by the microorganisms and used forthe synthesis of vanillin. After a period of several days, vanillin isextracted from the microorganisms and quantified. In addition, vanillinglucoside will be extracted and converted into vanillin throughdeglucosylation by beta-glucosidase activity in vitro. The amount ofrecovered vanillin will be quantified.

Similar experiments and quantification of vanillin synthesised as an endproduct as well as vanillin recovered from in vivo deglucosylation ofvanillin glucoside are performed in non-transformed microorganisms.

A greater amount of total vanillin extracted and recovered fromUDPG-glucosyl transferase expressing microorganisms as compared tonon-transformed microorganisms demonstrates that the presence of aheterologous UDPG-glucosyl transferase can lead to more ferulic acidbeing channeled into the synthesis of vanillin and its glucosylatedform, from which vanillin can later be recovered. Consequently, totalyield of vanillin can be increased through expression of a UDPG-glucosyltransferase.

Example 7 Facilitating Purification of an Organic Molecule byGlucosylation

The cell used in this example is the E. coli cell of Example 13, capableof producing vanillin glucoside.

In continuous fermentation the fermentor is inoculated with media forgrowth and the fermentation is started under aerobic conditions.

The first 12-18 hours is run for cell growth and after 12-18 hours thefermentor is fed with glucose for production of vanillin glucoside.During this part of the fermentation the growth rate is linear and it isanticipated that the limiting factor is the solubility of vanillinglucoside. From other corresponding glucosides it is known that thesolubility is app. 100 g/l at STP and increases at higher temperatures.

After approximately 30 hours the high concentration is reached andharvesting is started. The cells are separated and recycled to thefermentor.

The supernatant is either concentrated to the limit of vanillinglucoside solubility or directly passed through a column withbeta-glucosidase. The supernatant is re-circulated to the fermentor. Ifother products should be present, the vanillin solution can be passedover a cleaning column before recirculation. It is anticipated to have arow of columns where one is being used in the process while the othersare leaned and regenerated.

The product is recovered as crystals from the enzymatic treatment. Inorder to decrease the amount of re-circulated vanillin the temperatureis lowered in connection with enzyme treatment.

Example 9 Vanillin Sensitivity of Various Strains of E. coli

The three different E. coli strains TOP10, JM109, and KO1418 were grownfor 18 hours in the appropriate media, after which serial dilutions ingrowth medium (dilution factors 1,1/100, 1/10000 and 1/1000000) weremade. Droplets of these cell suspensions were applied to Petri dishescontaining solid LB growth medium with various concentrations ofvanillin, and the plates were incubated at the appropriate growthtemperature for 24 hours (E. coli), after which they were photographed.The percentual (w/v) concentration of vanillin at which growth of agiven microorganism at the 1/10000 dilution was not detectable, and atwhich growth at the 1/100 dilution was severely inhibited, was recorded.This number constituted the STV (Sensitivity To Vanillin) level. The STVnumbers for the different microorganisms studied can be seen in Table9.1.

TABLE 9.1 Vanillin sensitivity for various E. coli strains on solidgrowth medium Strain Genotype STV TOP10 F- mcrA Delta (mrr-hsdRMS-mcrBC)Phi8OlacZ Delta-M15 Delta-lacX74 0.12 recAl deoR araD139 Delta(ara-leu)7697 galU galK rpsL (StrR) endAl nupG JM109 F′traD36 lacIqDelta (lacZ) M15 proA+B+/ e14- (McrA-) Delta (lac- 0.14 proAB) thigyrA96 (NaIR) endAl hsdR17 (rK- mK-) relAl supE44 recA1 K01418 F- Delta(codB-lacI) 3 relAl? bglA677::Tn10 spoT1 bgLB676::Lambda-lacZ 0.18bglGo-67 thi-1

Example 10 PCR Amplification of S. bicolor UGT85B1, A. thaliana UGT89B1and R. serpentina Arbutin Synthase (AS) Genes

Roche Pwo polymerise and a DNA Engine Thermocycler were used for all PCRamplifications. The oligonucleotides referred to in the text aredescribed in Table 10.1.

TABLE 10.1 Oligonucleotides used in this study Oligo SEQ JH# NameSequence (5′-3′) ID NO  1 SB_GT_KK_F ATTAGAATTCATGGGCAGCAA  1CGCGCCGCCGCCG  2 SB_GT_KK_R ATTAAAGCTTTTACTGCTTGC  2 CCCCGACCAGCAG  3SB_GT_p ET_F CACCATGGGCAGCAACGCGCC  3 GCCGCCG  4 SB_GT_p ET_RTTACTGCTTGCCCCCGACCAG  4 CAG  5 SB_GT_S_F1 ATGGGCAGCAACGCGCCGCCT  5  6SB_GT_S_F2 CGCAGCTGCCAGGGAGGCCGG  6  7 SB_GT_S_F3 GCCTCCGCCGGCCTCGCCGCC 7  8 SB_GT_S_F4 CAGACCACCAACTGCAGGCAG  8  9 SB_GT_S_R1GAGAGGGAGAGGCCGTCGTCG  9 10 AT_GT_KK_F ATTAGAATTCATGAAAGTGAA 10CGAAGAAAACAAC 11 AT_GT_KK_R ATTAAAGCTTTTATTTGTTTA 11 GTCCTAAACTAACGAC 12AT_GT_pET_F ATGAAAGTGAACGAAGAAAAC 12 AAC 13 AT_GT_pET_RTTATTTGTTTAGTCCTAAACT 13 AACGAC 14 AT_GT_S_F1 ATGAAAGTGAACGAGGAAAAC 1415 AT_GT_S_F2 GAATCCCTCGTTTCGATTTCT 15 16 AT_GT_S_F3CTTGACGCACGTGAGGATAAC 16 17 AT_GT_S_F4 CCTGACACGGTGCCTGACCCG 17 18AT_GT_S_R1 CGGAGGGGATTGAAGGGTGGG 18 19 AS_GT_EC_KK_FATTAGAATTCATGGAACATAC 19 CCCGCACATT 20 AS_GT_EC_KK_RATTAGAATTCTTATGTACTGG 20 AAATTTTGTTC 21 AS_GT_EC_pET_FCACCATGGAACATACCCCGCA 21 CATT 22 AS_GT_EC_pET_R TTATGTACTGGAAATTTTGTT 22C 23 AS_GT_S_F1 ATGGAGCATACACCTCACAT 23 24 AS_GT_S_F2GACGGCCATGTGCCTGTCTC 24 25 AS_GT_S_F3 GGGGCAGTCTCCCATAATCA 25 26AS_GT_S_F4 AGGGTCTTAAAGTGGCCCTG 26 27 AS_GT_S_R1 TACGGGTCTCTATCCTAACA 2728 Pfba_F ATTAGAATTCAAAAATCACAG 28 GGCAGGGAAAC 29 Pfba_RATTAGGCGCGCCTCTAGAGTC 29 TCTTGTCCTGTATCGTCGGG 30 PpfkA_FATTAGAATTCTCAGTATAAAA 30 GAGAGCCAGAC 31 PpfkA_R ATTAGGCGCGCCTCTAGAGAC 31TACCTCTGAACTTTGGAAT 32 PgapA_F ATTAGAATTCTTGCTCACATC 32 TCACTTTAATC 33PgapA_R ATTAGGCGCGCCTCTAGAATA 33 TTCCACCAGCTATTTGTTA 34 PtpiA_FATTAGAATTCCAAAAAGCAAA 34 GCCTTTGTGCC 35 PtpiA_R ATTAGGCGCGCCTCTAGATTT 35AATTCTCCACGCTTATAAG 36 TcysB_F ATTAGGCGCGCCGGATCCTTT 36CTTGCGTTATTTTCGGCACC 37 TcysB_R ATTAAAGCTTGAAAAACCGCC 37 AGCCAGGCTTT 38SB_GT_EC_NP_F ATTATCTAGAATGGGCAGCAA 38 CGCGCCGCCGCCG 39 SB_GT_EC_NP_RATTAGGATCCTTACTGCTTGC 39 CCCCGACCAGCAG 40 AT_GT_EC_NP_FATTATCTAGAATGAAAGTGAA 40 CGAAGAAAACAAC 41 AT_GT_EC_NP_RATTAGGATCCTTACCACCGTT 41 CTATCTCCATCTTC 42 RS_GT_EC_NP_FATTATCTAGAATGGAACATAC 42 CCCGCACATT 43 RS_GT_EC_NP_RATTAGGATCCTTATGTACTGG 43 AAATTTTGTTCUGT85B1, UGT89B1 and AS for IPTG-Controlled Expression in E. coli

For amplification of UGT85B1 for use in the E. coli vector pKK223-3(Amersham-Pharmacia Biotech), the oligonucleotides JH#1 and JH#2 (Table10.1) were used, with the plasmid pSP19g10L-UGT85B1 (Jones et al., 1999,J Biol Chem 274: 35483) as template for the reaction. The reactionconditions employed were 94° C., 2 min., 1 cycle, 94° C., 30 sec.,gradient 50-60° C., 1 min., 72° C., 2 min., 30 cycles, followed by 72°C., 7 min., 1 cycle. The reaction contained 5% DMSO. Reaction samplescontaining a fragment of the expected size of 1.5 kb were combined, andused for ligation into the pCR-Blunt II-Topo vector. Clones containingEcoRI inserts of 1.5 kb were sequenced with the primers JH#5-9. A clonewith a correct DNA sequence was identified and named pJH400. The UGT85B1ORF was liberated from pJH 400 with EcoRI-HindII (these restrictionsites were included at the 5-termini of the primers) and inserted in anEcoRI-HindII digested pKK223-3 plasmid. A clone with a correct UGT85B1insert was identified and named pJH401.

For amplification of UGT85B1 for use in the E. coli vectorpET101-D/Topo, an identical PCR reaction was performed, only using theprimers JH#3 and 4. The same PCR program was employed, and a fragment ofthe correct size of 1.5 kb was directionally inserted in the expressionvector pET101-D/Topo. The inserts of several clones were sequenced usingprimers JH#5-9. One correct clone was named pJH402.

For amplification of UGT89B1 for use in the E. coli vector pKK223-3, theoligonucleotides JH#10 and JH#11 (Table 10.1) were used, with genomicArabidopsis thaliana DNA (var. Columbia Col-0) as template for thereaction. The reaction conditions employed were 94° C., 2 min., 1 cycle,94° C., 30 sec., gradient 50-60° C., 1 min., 72° C., 2 min., 30 cycles,followed by 72° C., 7 min., 1 cycle. Reaction samples containing afragment of the expected size of 1.4 kb were combined, and used forligation into the pCR-Blunt II-Topo vector. Clones containing EcoRIinserts of 1.4 kb were sequenced with the primers JH#14-18. A clone witha correct DNA sequence was identified and named pJH462. The UGT89B1 ORFwas liberated from pJH 462 with EcoRI-HindII (these restriction siteswere included at the 5′-termini of the primers) and inserted in anEcoRI-HindIII digested pKK223-3 plasmid. A clone with a correct UGT89B1insert was identified and named pJH463.

For amplification of UGT89B1 for use in the E. coli vectorpET101-D/Topo, an identical PCR reaction was performed, only using theprimers JH#12 and 13. The same PCR program was employed, and a fragmentof the correct size of 1.4 kb was directionally inserted in theexpression vector pET101-D/Topo. The inserts of several clones weresequenced using primers JH#14-18. One correct clone was named pJH406.

For amplification of AS for use in the E. coli vector pKK223-3, theoligonucleotides JH#19 and JH#20 (Table 10.1) were used, with theplasmid pQE60-AS (Arend et al., 2001, Biotechnol Bioeng 76:126) astemplate for the reaction. The reaction conditions employed were 94° C.,2 min., 1 cycle, 94° C., 30 sec., gradient 48-55° C., 1 min., 72° C., 2min, 30 cycles, followed by 72° C., 7 min., 1 cycle. Reaction samplescontaining a fragment of the expected size of 1.4 kb were combined, andused for ligation into the pCR-Blunt II-Topovector. Clones containingEcoRI inserts of 1.5 kb were sequenced with the primers JH#23-27. Aclone with a correct DNA sequence was identified and named pJH409. TheAS ORF was liberated from pJH409 with EcoRI (EcoRI sites were includedat the 5′-termini of both primers) and inserted in an EcoRI digestedpKK223-3 plasmid. A done with a correct AS insert in the correctorientation was identified and named pJH410.

For amplification of AS for use in the E. coli vector pET101-D/Topo, anidentical PCR reaction was performed, only using the primers JH#21 and22. The same PCR program was employed, and a fragment of the correctsize of 1.4 kb was directionally inserted in the expression vectorpET101-D/Topo. The inserts of several clones were sequenced usingprimers JH#23-27. One correct clone was named pJH411.

UGT85B1, UGT89B1 and AS for Constitutive Expression in E. coli

A series of tailored expression systems for UGT85B1 and AS wereconstructed in which the glucosyl transferase genes were controlled byone of four glycolytic E. coli gene promoters: fba (primers JH#28 and29), pfkA (311#30 and 31), tpiA (JH#32 and 33) and gapA (JH#34 and 35)promoters, and all by the E. coli cysB terminator (primers JH#27 and 28)sequences. All constructions were based on the following scheme: Thepromoter fragment was PCR amplified from E. coli DH5a genomic DNA,inserted BamHI-Asa (these sites were present in the primers) in pKOL30(Olesen et al., 2000, Yeast 16: 1035). In the resulting construct thecysB fragment was then inserted AscI-HindIII (sites present in primers).Finally, in the resulting construct, PCR amplified UGT85B1 (primersJH#38 and 39), UGT89B1 (primers JH#40 and 41) or AS (JH#42 and 43) werethen inserted XbaI-EcoRI (these sites were present inside the AscI sitesin the 3′-end primer used for promoter amplification and in the 5′-endprimer used for the terminator amplification, as well as in the primersused for amplification of the UGT and AS genes). The PCR reactionconditions employed were 94° C., 2 min., 1 cycle, 94° C., 30 sec., 55°C., 1 min. (for promoter and terminator fragments, as well as UGTfragments) or 48° C., 1 min (for AS fragment), 72° C., 2 min, 30 cycles,followed by 72° C., 7 min., 1 cycle. For amplification of UGT85B1, 5%DMSO was included. Reaction samples containing a fragment of theexpected sizes were combined, gel purified and used for cloningexperiments as described above.

The resulting plasmids were pJH430 (fba-UGT85B1), pJH431 (pfkA-UGT85B1),pJH432(gapAA-UGT85B1), pJH433 (tpiA-UGT85B1), pJH-1434 (fba-UGT89B1),pJH435 (pfkA-UGT89B1), Pjh436 (gapA-UGT89B1), pJH437 (tpiA-UGT89B1),pJH438 (fba-AS), pJH439 (pfkA-AS), pJH440 (gapA-AS) and pJH441(tpiA-AS).

Example 11 Vanillin Detoxification by Expression of UGT or AS Genes E.coli

The E. coli strains TOP10, JM109, and KO1418 were all transformed withthe constructed plasmids pJH401, pJH402, pJH411 and pJH412, and pKK223-3as control, employing standard transformation protocols. Transformantswere selected for ampicillin resistance, and two transformants of eachE. coli strain with each plasmid were kept for expression experiments.The E. coli transformants were inoculated from plate cultures into 2 mlliquid growth medium (LB medium containing ampicillin at 100 μg/ml), andallowed to grow for 20 hours at 37° C. The precultures were diluted 100times 10⁴ times and 10⁶ times in growth medium, and 4 μl droplets ofthese cell suspensions were applied to the surface of Petri dishescontaining solid LB-ampicillin medium containing varying concentrationsof vanillin (based on the STV determinations described above), andwithout or with (to induce gene expression) 1 mM isopropylthiogalactoside (IPTG). The plates were incubated at 37° C. for 24hours, after which growth on the various concentrations of vanillin wasmonitored and recorded. The results are summarized in Table 11.1.

TABLE 11.1 Effect of IPTG-induced expression of S. bicolor UGT85B1 or R.serpentina AS on the toxicity of vanillin on three different strains ofE. coli. −: No growth; +: weak growth; ++ good growth. E. coli strain\IPTG % Vanillin 0% 0.08% 0.12% 0.16% 0.2% induction JM109 [pKK223-3] ++++ ++ − − No ++ ++ ++ − − Yes JM109 [pJH401] ++ ++ ++ − − No ++ ++ ++ −− Yes JM109 [pJH402] ++ ++ ++ + − No ++ ++ ++ ++ − Yes JM109 [pJH410] ++++ ++ ++ − No ++ ++ ++ ++ − Yes KO1418 [pKK223-3] ++ ++ ++ − − No ++ ++++ ++ − Yes K01418 [Pjh401] ++ ++ ++ ++ − No ++ ++ ++ ++ − Yes K01418[pJH402] ++ ++ ++ ++ − No ++ ++ ++ ++ − Yes K01418 [pJH410] ++ ++ ++ ++− No ++ ++ ++ ++ ++ Yes

From these experiments we conclude that expression of S. bicolor UGT85B1is possible in some E. coli strains and with some types ofIPTG-inducible gene promoters, and that a stronger vanillindetoxification can be obtained by expression of the AS gene, but only inan E. coli strain in which the phospho-β-glucosidase encoding bgl locushas been inactivated (strain KO1418).

For experimentation with constitutive expression of UGT85B1 and AS, theE. coli strains JM109, and KO1418 were transformed with the constructedplasmids pJH 430, pJH431, pJH432, pJH433, pJH434, pJH435, pJH436,pJH437, pJH438, pJH439, pJH440, and pJH441, and pKOL30 as control,employing standard transformation protocols. Transformants were selectedfor ampicillin resistance, and two transformants of each E. coli strainwith each plasmid were kept for expression experiments. The E. colitransformants were inoculated from plate cultures into 2 ml liquidgrowth medium (LB medium containing ampicillin at 100 μg/ml), andallowed to grow for 20 hours at 37° C. The precultures were diluted 100times 10⁴ times and 10⁶ times in growth medium, and 4 μl droplets ofthese cell suspensions were applied to the surface of Petri dishescontaining solid LB-ampicillin medium containing varying concentrationsof vanillin (based on the STV determinations described above). Theplates were incubated at 37° C. for 24 hours, after which growth on thevarious concentrations of vanillin was monitored and recorded. Theresults are summarized in Table 11.2. The results with E. coli strainsJM109 and KO1418 with the plasmids pJH430, pJH431, pJH432 and pJH433 aresummarized in Table 10.2 below.

TABLE 11.2 Effect of constitutive expression of S. bicolor UGT85B1 or R.serpentina AS on the toxicity of vanillin on two different strains of E.coli. % Vanillin E. coli strain 0% 0.08% 0.12% 0.16% JM109 [pKOL30] ++++++ ++ − JM109 [pJH 430] +++ +++ +++ ++ JM109 [pJH 431] +++ +++ +++ ++JM109 [pJH 432] +++ +++ +++ + JM109 [pJH 433] +++ +++ +++ + KO1418[pKOL30] +++ +++ ++ + KO1418 [pJH430] +++ +++ +++ +++ KO1418 [pJH431]+++ +++ +++ +++ KO1418 [pJH432] +++ +++ +++ + KO1418 [pJH433] +++ ++++++ +++ − No growth; + weak growth; ++ growth; +++ strong growth.

From these experiments we conclude that constitutive expression ofglucosyl transferase genes in 15 E. coli strain JM109 results invanillin detoxification

Example 12 Vanillin Glucoside (VG) Production in UGT85B1-, UGT89B1- orAS-Expressing Strains of E. coli

Several E. coli strains expressing UGT85B1 or AS are tested for VGproduction by growth in liquid growth medium containing sublethalvanillin concentrations. The strains tested are JM109 and KO1418containing either of the following plasmids: pKK223-3, pJH401, pJH402,pJH406, pJH463, pJH410, pKOL30, pJH430, p311431, pJH432, pJH433, pJH434,pJH435, pJH436, pJH437, pJH438, pJH439, pJH440 and pJH441.

The E. coli strains are inoculated over night at 37° C. in 2 ml LBmedium containing 100 μg/ml ampicillin, and then diluted into 50 ml ofthe same growth medium (0.1 ml o.n. culture). Growth proceeds at 37° C.for 2 hours, and then IPTG is added to a concentration of 1 mM (0.5 ml100 mM stock) to those strains containing IPTG-inducibleUGT/AS-expression plasmids. The cell suspensions are then incubated at28° C. for 1 hour, after which vanillin is added to a concentration of0.05% (83 μl 30% ethanol stock). Growth then proceeds at 28° C. for 24hours. Cultures are centrifuged LC-MS are employed to determine VGcontent in growth supernatant as well as lysates of cell pellets.

In another set of experiments, the same E. coli strains are grown in asimilar way, but instead of vanillin, ¹⁴C-labelled vanillin (5 mCi of 50mCi/mol) is added to the growing cultures, after which growth proceeds28° C. for 1-24 hours. Supernatant samples are taken regularly as arecell samples. Cell lysates are produced and both growth supernatants andcell lysates are subjected to TLC (thin layer chromatography) asdescribed (Jones et al., 1999, J Biol Chem 274: 35483). Employingautoradiography, radioactive vanillin and radioactive vanillin glucosideare detected.

By both of the above described analyses we are able to detect thepresence of vanillin glucoside from cells expressing UGT or AS geneswhile no vanillin glucoside can be detected from growth of cells notexpressing UGT or AS genes.

Example 13 Establishment of a De Novo Biosynthesis Pathway for theSupply of Vanillin to Microbial Expressed Glucosytransferases

To establish a microbial pathway for the conversion of glucose tovanillin three heterologous enzymatic activities are expressed in theUDPG-glucosyltransferase expressing microorganism.

The first enzymatic activity is a 3-dehydroshikimate dehydratase, which“taps” out a distant vanillin precursor from the common aromatic aminoacid biosynthetic pathway, namely 3-dehydroshikimate, and converts it toprotocatechuic acid. 3-Dehydroshikimate dehydratase (3DHD) genes areknown from Neurospora crassa (Ruthledge, 1984, Gene 32: 275),Aspergillus nidulans (Hawkins et al, 1985, Curr Genet 9: 305), Podosporapauciseta (GenBank accession # AL627362) and Acinetobacter cakoaceticus(Elsemore & Ornston, 1995, J Bacteriol 177: 5971). The next enzymenecessary is an aromatic carboxylic acid reductase (ACAR) that canconvert protocatechuic acid to protocatechualdehyde. ATP-dependent ACARactivities are found in certain actinomycetes (Nocardia sp.) (use ofNocardia ACAR patented: Rosazza & Li, 2001, U.S. Pat. No. 6,261,814B1),in Neurospora crassa (Gross & Zenk, 1969, Eur J Biochem 8: 413) (use ofACAR enzyme preparation patented: Frost, 2002, U.S. Pat. No.6,372,461B1) and in a range of basidiomycetes, so called “white-rot”fungi, which are lignin degraders (e.g. Trametes, Dichomitus,Bjerkandera and Pleurotus (“Oyster mushroom”) sp. (Hage et al., 1999,Appl Microbiol Biotechnol 52: 834). Data for a short N-terminal proteinsequence from the Nocardia enzyme is available (Li & Rosazza, 1997, J.Bacteriol 179: 3482), and the full nucleotide sequence of the gene hasrecently been published (He et al., 2004, Appl Env Microbiol70:1874-1881). Finally, a 3-amethylation is necessary for the finalconversion to vanillin. The candidate enzyme for this purpuse is astrawberry S-adenosylmethionine:furaneol O-methyltransferase gene(FaOMT) (Wein et al., 2002, Plant J 31: 755), as this enzyme ratherspecifically methylates protocatechuic aldehyde at the 3-Oposition.Alternative methylases include aspen (Bugos et al., 1991), Plant MolBiol 17: 1203), almond (Garcia-Mas et al, 1995, Plant Phys 108:1341) andVanilla planifolia (Pak et al., 2004, Plant Cell Rep: 11) OMTs. To avoidthe accumulation of toxic intermediates the first gene expressed in afunctional UGT-expressing microbial strain will be the methyltransferase gene. When this has been seen to work (i.e. producingvanillin glucoside from protocatechualdehyde), the aldehydedehydrogenase is introduced, etc., until the intrinsic3-dehydroshikimate-producing pathway is reached.

The strawberry FaOMT gene is isolated by PCR, using Fragrada×ananassa(strawberry) cDNA as template DNA. The cDNA is isolated from maturing F.ananassa var. Elanta using the QBiogene Fastprep Pro Green kit, and fromthe resulting total RNA preparation cDNA is synthesized employing theInvitrogen Superscript II Reverse transcriptase. This cDNA preparationis used for PCR amplification using FaOMT ORF-specific primers and Pwopolymerase (Roche Biochemicals). The resulting 1.1 kb FaOMT-containingDNA fragment is isolated and inserted between the XbaI and BamHI sitesin the inducible E. coli expression vector pJFI-X1, resulting in plasmidpJH-X2.

E. coli strain JH1, which corresponds to E. coli JM109 containingplasmid pJH430 (expressing UGT85B1 from the E. coli fba promoter) istransformed with plasmid pJH-X2. The resulting E. coli strain JH2 isgrown in liquid LB growth medium to which protocatechualdehyde is added.Expression is induced. The culture supernatant of the outgrown cultureis subjected to LC-MS, and vanillin glucoside is identified, meaningthat a biosynthetic pathway that can convert protocatechualdehyde tovanillin glucoside has been established.

An ACAR gene that is effective in the conversion of protocatechualdehydeto vanillin is isolated in the following manner cDNA is synthesized fromtotal RNA extracted from either of the white rot fungi Pleurotusosfreatus or Trametes gibbosa by the use of Invitrogen Superscript IIReverse transcriptase. A phagemid cDNA library is produced using theStratagene cDNA library construction system. DNA prepared from theselibraries is used to isolate the 5′-region of white rot ACAR genes,taking advantage of the Nocardia ACAR nucleotide sequence information.The forward primer is identical to vector sequences present immediatelyupstream of the cDNA insertion location. The reverse primer ishomologous to the area of the Nocardia ACAR. gene that has the highestdegree of evolutionary conservation, when the deduced amino acidsequence of this gene is compared to the deduced amino acid sequence ofother putative ACAR genes found in the public sequence databases (bycomparison with Nocardia ACAR). Several such primers with “basewobbling” at various nucleotide positions (i.e. degenerate primers) areused together with the forward primer in a PCR reaction using cDNAlibrary DNA from either of the two libraries described above, and HighFidelity Plus polymerase (Roche Biocehmicals).

Optimizing for annealing temperature and magnesium ion concentration, aPCR fragment of appr. 0.8 kb is isolated. By subcloning and nucleotidesequence analysis, this fragment is shown to encode the 5′-region of R.ostreatus or T. gibbosa ACAR. The obtained sequence information is usedto define an ACAR-internal forward oligonucleotide primer that can beused together with a reverse primer identical to library vectorsequences present distal to the 3′end of the cDNA inserts, to amplifythe 3′-end of the P. ostreatus or T. gibbosa ACAR genes. Aftersequencing of the gene fragments thus isolated, a ACAR 3′-end specificoligonucleotide primer is defined, and employed together with a 5′-endspecific primer, to obtain full length P. ostreatus or T. gibbosa ACAR,in a final PCR reaction. The cDNA insert of this clone is subjected toDNA sequencing analysis, and after confirmation of the ACAR. genesequence, the gene is inserted into the An ACAR gene that is effectivein the conversion of protocatechualdehyde to vanillin is isolated in thefollowing manner: cDNA is synthesized from total RNA extracted fromeither of the white rot fungi Pleurotus ostreatus or Trametes gibbosa bythe use of Invitrogen Superscript II Reverse transcriptase. A phagemidcDNA library is produced using the Stratagene cDNA library constructionsystem. DNA prepared from these libraries is used to isolate the5′-region of white rot ACAR genes, taking advantage of the Nocardia ACARnucleotide sequence information. The forward primer is identical tovector sequences present immediately upstream of the cDNA insertionlocation. The reverse primer is homologous to the area of the NocardiaACAR gene that has the highest degree of evolutionary conservation, whenthe deduced amino 20 acid sequence of this gene is compared to thededuced amino acid sequence of other putative ACAR genes found in thepublic sequence databases (by comparison with Nocardia ACAR). Severalsuch primers with “base wobbling” at various nucleotide positions (i.e.degenerate primers) are used together with the forward primer in a PCRreaction using cDNA library DNA from either of the two librariesdescribed above, and High Fidelity Plus polymerase (Roche Biocehmicals).Optimizing for annealing temperature and magnesium ion concentration, aPCR fragment of appr. 0.8 kb is isolated. By subcloning and nucleotidesequence analysis, this fragment is shown to encode the 5′-region of P.ostreatus or T. gibbosa ACAR. The obtained sequence information is usedto define an ACAR-internal forward oligonucleotide primer that can beused together with a reverse primer identical to library vectorsequences present distal to the 3′end of the cDNA inserts, to amplifythe 3′-end of the P. ostreatus or T. gibbosa ACAR genes. Aftersequencing of the gene fragments thus isolated, a ACAR 3′-end specificoligonucleotide primer is defined, and employed together with a 5′-endspecific primer, to obtain full length P. ostreatus or T. gibbosa ACAR,in a final PCR reaction. The cDNA insert of this done is subjected toDNA sequencing analysis, and after confirmation of the ACAR genesequence, the gene is inserted into the S. cerevisiae expression vectorpJH413, resulting in plasmid pJH413-X1, the E. coli expression vectorpJH-X2, resulting in plasmid pJH-X3. E. coli strain JH1 (expressingUGT85B1) is transformed with plasmid pJH-X3. The resulting E. colistrain JH3 is grown in liquid LB growth medium to which protocatechuicacid is added. Expression is induced. The culture supernatant of theoutgrown culture is subjected to LC-MS, and vanillin glucoside isidentified, meaning that a biosynthetic pathway that can convertprotocatechuic acid to vanillin glucoside has been established.

A 3DHD gene is isolated from Podospora pauciseta in the followingmanner: Genomic DNA is isolated from P. pauciseta using the QBiogeneFastprep DNA system, and the 3DHD gene is PCR amplified using thisgenomic DNA as template from the reaction with P. pauciseta3DHD-specific primers, and the Pwo polymerase (Roche Biochemicals). Theresulting 1.1 Id, 3DBD gene fragment is inserted between the BamHI andXbaI sites of the E. coli expression vector pJH-X3, resulting in plasmidpJH Van. E. coli strain JH1 (expressing UGT85B1) is transformed withplasmid pJH-Van.

The resulting E. coli strain JH4 is grown in liquid LB growth medium.Expression is induced. The culture supernatant of the outgrown cultureis subjected to LC-MS, and vanillin glucoside is identified, meaningthat a biosynthetic pathway that can convert glucose to vanillinglucoside has been established.

E. coli strain JM109 is now transformed with plasmid pJH-Van. Theresulting strain, JH5 now contains a biosynthesis pathway for vanillinproduction from glucose, while strain JH4 contains a biosynthesispathway for vanillin production in addition to the glucosyltransferase-encoding UGT85B1 gene. Strains JH4 and JH5 are both grown inliquid LB growth medium, and gene expression is induced. By the meansdescribed above we compare vanillin production in strain JH5 withvanillin glucoside production in strain JH4.

We observe that the E. coli strain containing a biosynthesis pathway forvanillin production in addition to a glucosyl transferase gene (strainJH4) produces higher amounts (on a molar basis) of vanillin glucoside ascompared to the amounts of the corresponding vanillin aglucone.

Example 14 Establishment of a Vanillin De Novo Biosynthesis Pathway inSaccharomyces cerevisiae Yeast

To establish a microbial pathway for the conversion of glucose tovanillin three heterologous 10 enzymatic activities are obtained bymolecular genetic techniques and expressed in Saccharomyces cerevisiae.

The first enzymatic activity is a 3-dehydroshikimate dehydratase, which“taps” out a distant vanillin precursor from the common aromatic aminoacid biosynthetic pathway, namely 3-dehydroshikimate, and converts it toprotocatechuic acid. 3-Dehydroshikimate dehydratase (3DHD) genes areknown from Neurospora crassa (Ruthledge, 1984, Gene 32: 275),Aspergillus nidulans (Hawkins et al., 1985, Curr Genet 9: 305),Podospora pauciseta (GenBank accession # AL627362) and Acinetobactercalcoaceticus (Elsemore & Ornston, 1995, J Bacteriol 177: 5971). Thenext enzyme necessary is an aromatic carboxylic acid reductase (ACAR)that can convert protocatechuic acid to protocatechualdehyde.ATP-dependent ACAR. activities are found in certain actinomycetes(Nocardia sp.) (use of Nocardia ACAR patented: Rosazza & Li, 2001, U.S.Pat. No. 6,261,814B1), in Neurospora crassa (Gross & Zenk, 1969, Eur JBiochem 8: 413) (use of ACAR enzyme preparation patented: Frost, 2002,U.S. Pat. No. 6,372,461B1) and in a range of basidiomycetes, so-called“white-rot” fungi, which are lignin degraders (e.g. Trametes,Dichomitus, Bjerkandera and Pleurotus (“Oyster mushroom”) sp. (Hage etal., 1999, Appl Microbiol Biotechnol 52: 834). Data for a shortN-terminal protein sequence from the Nocardia enzyme is available (Li &Rosazza, 1997, J Bacteriol 179: 3482), and the full nucleotide sequenceof the gene has recently been published (He et al., 2004, Appl EnvMicrobiol 70:1874-1881). Finally, a 3-O-methylation is necessary for thefinal conversion to vanillin. The candidate enzyme for this purpuse is astrawberry S-adenosylmethionine:furaneol O-methyltransferase gene(FaOMT) (Wein et al., 2002, Plant J 31:755), as this enzyme ratherspecifically methylates protocatechuic aldehyde at the 3-O position.Alternative methylases include aspen (Bugos et al., 1991), Plant MolBiol 17: 1203), almond (Garcia-Mas et al., 1995, Plant Phys 108:1341)and Vanilla planifolia (Pak et al., 2004, Plant Cell Rep: 11) OMTs.

The strawberry FaOMT gene was isolated by PCR, using Fragraria×ananassa(strawberry) cDNA as template DNA. The cDNA was isolated from maturingF. ananassa var. Elanta using the QBiogene Fastprep Pro Green kit, andfrom the resulting total RNApreparation cDNA was synthesized employingthe Invitrogen Superscript II Reverse transcriptase. This cDNApreparation is used for PCR amplification using primers #1 and #2 (Table14.1) and Pwo polymerase (Roche Biochemicals). The resulting 1.1 kbFaOMT-containing DNA fragment was isolated and inserted between the XbaIand BamHI sites of the S. cerevisiae expression vector pJH413, resultingin plasmid pJH471. The expression cassette (Ptpi1-FaOMT-Tpi1) frompJH471 was then transferred NotI-NotI to the yeast integration vectorpYC050 (Hansen et al., 2003, FEMS Yeast Res 4:323-327), resulting in theplasmid 011494. Ten μg of plasmid pJH494 was linearized by restrictiondigestion with PsiI, and the resulting preparation was used to transformS. cerevisiae yeast strain JH1 to NOURSEOTHRICIN resistance, resultingin yeast strain FSC58.

A 3DHD gene was isolated from Podospora pauciseta in the followingmanner: Genomic DNA was isolated from P. pauciseta using the QBiogeneFastprep DNA system, and the 3DHD gene was PCR amplified using thisgenomic DNA as template from the reaction with P. pauciseta3DHD-specific primers #3 and #4 (Table14.1), and the Pwo polymerase(Roche Biochemicals). The resulting 1.1 kb 3DHD gene fragment wasinserted between the BamHI and XbaI sites of the S. cerevisiaeexpression vector pJH413, resulting in plasmid pJH485. The expressioncassette (Ptpi1-3DSD-Ttpi1) from pJH485 was then transferred NotI-Notito the yeast integration vector pYC070 (Hansen et al., 2003, FEMS YeastRes 4:323-327), resulting in the plasmid Pjh500. Ten μg of plasmidPjh500 was linearized by restriction digestion with Bsu36I, and theresulting preparation was used to transform S. cerevisiae yeast strainFSC58 to aureobasidin A resistance, resulting in yeast strain FSC67.

Synthetic complete yeast medium (50 ml, in 250 ml Erlenmeyer flasks) wasinoculated with 50 μl of an over night culture of S. cerevisiae yeaststrain FSC67 grown in the same medium, and the cultures allowed to growat 30° C., 150 rpm shaking. One ml samples were taken at 24 h, and 500μl of the cell-free growth supernatants precipitated with an equalvolume of 100% methanol.

The resulting supernatants were subjected to HPLC analysis on an Agilent1100 Series HPLC system, using a Zorbax SB-C18 column (3.5 μm), and anelution profile as follows: A gradient of H₂O (pH 2.3 with112SO4)-acetonitrile from 0 to 40% acetonitrile in 3 min., 40%acetonitrile for 1 min., a gradient from 40 to 80% acetonitrile for 2min., and a gradient from 80 to 90% acetonitrile for 1 min., followed by90% acetonitrile for 1 min. Protocatechuic acid and vanillic acid weredetected by a diode array detector at 250 nm and 210 nm, and thefollowing elution times were found: protocatechuic acid, 5.3 min, andvanillic acid, 5.9 min. The result of the experiment was that strainFSC67 was able to produce 0.3 g/l of protocatechuic acid and 0.01 g/l ofvanillic acid, with no other precursor than glucose. It is anticipatedthat the FaOMT methyltransferase is much more efficient withprotocatechuic aldehyde than with protocatechuic acid as substrate, andhence that incorporation of a carboxylic acid reductase (ACAR) enzyme instrain FSC67 will result in a much better conversion ratio of the formedprotocatechuic acid as well as the de novo formation of vanillin fromglucose.

An ACAR. gene that is effective in the conversion ofprotocatechualdehyde to vanillin is isolated in the following mannercDNA is synthesized from total RNA extracted from either of the whiterot fungi Pleurotus ostreatus or Trametes gibbosa by the use ofInvitrogen Superscript II Reverse transcriptase. A phagemid cDNA libraryis produced using the Stratagene cDNA library construction system. DNAprepared from these libraries is used to isolate the 5′-region of whiterot ACAR genes, taking advantage of the Nocardia ACAR nucleotidesequence information.

The forward primer is identical to vector sequences present immediatelyupstream of the cDNA insertion location. The reverse primer ishomologous to the area of the Nocardia ACAR gene that has the highestdegree of evolutionary conservation, when the deduced amino acidsequence of this gene is compared to the deduced amino acid sequence ofother putative ACAR genes found in the public sequence databases (bycomparison with Nocardia ACAR). Several such primers with “basewobbling” at various nucleotide positions (i.e. degenerate primers) areused together with the forward primer in a PCR reaction using cDNAlibrary DNA from either of the two libraries described above, and HighFidelity Plus polymerase (Roche Biocehmicals). Optimizing for annealingtemperature and magnesium ion concentration, a PCR fragment of appr. 0.8kb is isolated. By subcloning and nucleotide sequence analysis, thisfragment is shown to encode the 5′-region of P. ostreatus or T. gibbosaACAR. The obtained sequence information is used to define anACAR-internal forward oligonucleotide primer that can be used togetherwith a reverse primer identical to library vector sequences presentdistal to the 3′end of the cDNA inserts, to amplify the 3′-end of the P.ostreatus or T. gibbosa ACAR genes. After sequencing of the genefragments thus isolated, a ACAR 3′-end specific oligonucleotide primeris defined, and employed together with a 5′-end specific primer, toobtain full length P. ostreatus or T. gibbosa ACAR, in a final PCRreaction. The cDNA insert of this clone is subjected to DNA sequencinganalysis, and after confirmation of the ACAR gene sequence, the gene isinserted into the S. cerevisiae expression vector pJH413, resulting inplasmid pJH413-X1. The Notl-Notl expression cassette is transferred topYC040 (Hansen et al., 2003, FEMS Yeast Res 4:323-327), thus creatingplasmid pJH413-X2. Ten μg of this plasmid is linearized using anappropriate restriction enzyme, and the preparation used to transform S.cerevisiae strain FSC67 to hygromycin B-resistance, thus creating yeaststrain FSC67-X1.

Finally, synthetic complete medium (50 ml, in 250 ml Erlenmeyer flasks)is inoculated with 50 of an over night culture of S. cerevisiae yeaststrain FSC67-X1 grown in the same medium, and the cultures allowed togrow at 30° C., 150 rpm shaking. One ml samples are taken at 0 h, 24 h,and 48 h, and 500 μl of the cell-free growth supernatants precipitatedwith an equal volume of 100% methanol. The resulting supernatants aresubjected to HPLC analysis. We observe the formation of significantamounts of vanillin from glucose as precursor with yeast strainFSC67-X1, and thus we conclude that a de novo vanillin biosynthesispathway has been obtained.

TABLE 14.1 Oligonucleotides used in example 14. Oligonudeotide 5′-3′Sequence #1, SEQ ID NO: 44 ATTATCTAGAATGGGTTC CACCGGCGAGACTCAG#2, SEQ ID NO: 45 ATTAGGATCCTCAGATCT TCTTAAGAAACTCAATG #3, SEQ ID NO: 46ATTATCTAGAATGCCTTC CAAACTCGCCATCACTTC #4, SEQ ID NO: 47ATTAGGATCCTTACAAAG CCGCTGACAGCGACAG

Example 15 In Vivo Production of Vanillin Glucoside in Saccharomycescerevisiae Yeast

A S. cerevisiae yeast strain expressing AS was tested for VG productionby fed-batch growth in a 2 liter fermentor vessel, in liquid growthmedium containing a sublethal vanillin concentration. 5 The straintested was JH6 (adh6 adh7) containing plasmid pJH413 (JH6 [pJH413]).

Plasmid pJH413 was constructed in the following way: The arbutinsynthase (AS) gene was amplified using the oligonucleotide primers #1and #2 (Table 15.1), with the plasmid pQE60-AS (Arend et al., 2001,Biotechnol Bioeng 76:126) as template for the reaction. The reactionconditions employed were 94° C., 2 min., 1 cycle, 94° C., 30 sec.,gradient 48-55° C., 1 min., 72° C., 2 min., 30 cycles, followed by 72°C., 7 min, 1 cycle. Reaction samples containing a fragment of theexpected size of 1.4 kb were combined, and used for ligation into thepCR-Blunt II-Topo vector. Clones containing EcoRI inserts of 1.5 kb weresequenced with the primers JH#23-27 (Table 10.1 in Example 10). A clonewith a correct DNA sequence was identified and from this plasmid the ASORF was liberated XbaI and BamHI (such sites were included at the5′-termini of the PCR amplification primers) and inserted into thecorresponding sites of the yeast expression vector p111259 (derivativeof plasmid pJH235; Hansen et al., 2003, FEMS Yeast Res 2:137-149). Aclone with a correct AS insert was identified and named pJH413.

Strain JH6 was transformed with plasmid pJH413 and inoculated for 48 hat 30° C. in 2 ml SC-ura medium containing, and then all of this cultureis diluted into 1.8 liter of the same growth medium. The culture wasgrown with oxygenation for 24 hours, after which more glucose (20·g/l)was added, along with 5 mM of vanillin. At T=48 h another 10 g/l ofglucose and 5 mM vanillin was added. A 10 ml sample was taken at T=72 h,and the cellular as well as extracellular content of vanillin and itsderivatives was extracted with hot ethanol The resulting extract wasconcentrated ten times under vacuum, and the concentrated cultureextract subjected to LC-MS analysis. A part of the concentrated culturesample was treated with almond β-glucosidase, and then subjected toLC-MS analysis. The culture content of the β-glucosides of vanillin,vanillic acid and vanillyl alcohol was determined by LC-MS analysis.

The conclusion is that vanillin glucoside can be formed in vivo inSaccharomyces cerevisiae by the glucosylation of vanillin. As vanillinglucoside is much less toxic to microbial organisms than is the aglyconvanillin, we conclude that expression of appropriate UDP-glucoseglycosyltransferases in Saccharomyces yeast allows for overproduction ofvanillin.

TABLE 15.1 Oligonucleotides used in example 15. Oligonucleotide 5′-3′Sequence #1, SEQ ID NO: 48 ATTATCTAGAATGGAA CATACACCTCACATT#2, SEQ ID NO: 49 ATTAGGATCCTTATGT ACTGGAAATTTTGTTC

Example 16 Overproduction of Protocatechuic Acid in Saccharomycescerevisiae by Expression of the Arabidopsis thaliana UGT89B1Glucosyltransferase

A Saccharomyces cerevisiae strain producing protocatechuic acid due toexpression of the Podospora pauciseta 3-dehydroshikimate dehydratase(3DSD) gene was constructed, and used to show overproduction ofprotocatechuic acid due to expression of the Arabidopsis thalianaUGT89B1 glucosyltransferase.

S. cerevisiae strain JH1 was transformed with linearized plasmid pJH500(as described in example 14) in order to allow for overexpression of theP. pauciseta 3-dehydroshikimate dehydratase, in the manner described inExample 14. The resulting yeast strain was denoted FSC59, and thisstrain was used for transformation with the UGT89B1 yeast expressionplasmid pJH468.

Plasmid pJH468 was constructed in the following way: The UGT89B1 genewas PCR amplified using the oligonucleotides #1 and #2 (Table 16.1),with genomic Arabidopsis thaliana DNA (var. Columbia Col-0) as templatefor the reaction. The reaction conditions employed were 94° C., 2 min.,1 cycle, 94° C., 30 sec., gradient 50-60° C., 1 min., 72° C., 2 min., 30cycles, followed by 72° C., 7 min., 1 cycle. Reaction samples containinga fragment of the expected size of 1.4 kb were combined, and used forligation into the pCR-Blunt II-Topo vector. Clones containing EcoRIinserts of 1.4 kb were sequenced with the primers JH#14-18 (Table 10.1,Example 10). A done with a correct DNA sequence was identified and namedpJH407. The UGT89B1 ORF was liberated from pJH407 with XbaI-BamHI (theserestriction sites were included at the 5′-termini of the primers) andinserted in an XbaI-BamHI digested pJH259 plasmid. A done with a correctUGT89B1 insert was identified and named pJH408. The URA3 selectionmarker of this plasmid was exchanged with the G418R selection marker(from plasmid pYC030, see Olesen et al., 2000, Yeast 16:1035), and theyeast “origin of replication region” was removed by restrictiondigestion with Fsel, followed by relegation, thus creating the yeastintegration plasmid pJH468.

Ten μg of plasmid pJH468 was linearized by restriction digestion withPsiI, and the resulting preparation was used to transform S. cerevisiaeyeast strain JFSC59 to nourseothricin resistance, resulting in yeaststrain FSC60.

Synthetic complete yeast medium (50 ml, in 250 ml Erlenmeyer flasks) wasinoculated with 50 of an over night culture of S. cerevisiae yeaststrain JH1, FSC59 and FSC60 grown in the same medium, and the culturesallowed to grow at 30° C., 150 rpm shaking. One ml samples were taken at48 h, and 500 μl of the cell-free growth supernatants precipitated withan equal volume of 100% methanol. The resulting supernatants weresubjected to HPLC analysis on an Agilent 1100 Series HPLC system, usinga Zorbax SB-C18 column (3.5 μm), and an elution profile as follows: Agradient of H₂O (pH 2.3 with H₂SO₄)-acetonitrile from 0 to 40%acetonitrile in 3 min., 40% acetonitrile for 1 min., a gradient from 40to 80% acetonitrile for 2 min., and a gradient from 80 to 90%acetonitrile for 1 min., followed by 90% acetonitrile for 1 min.Protocatechuic acid (PA) and protocatechuic acid-β-D-glucoside (PAG)were detected by a diode array detector at 250 nm and 210 nm, and thefollowing elution times were found: protocatechuic acid, 5.4 min, andprotocatechuic acid-β-D-glucoside, 4.7 min. The identity of PAG wasconfirmed by LC-MS analysis.

The result of the experiment was that strain FSC59 was able to produce0.43 g/l of PA while strain FSC60 produced 0.28 g/l of PA and 0.69 g/lof PAG. When the sample from strain FSC60 were treated with almondβ-glucosidase, the result was an increase in the PA content to 0.62 g/lacid, corresponding to an overproduction in strain FSC60 of PA of morethan 40%, as compared to strain FSC59, in which the UGT89B1 glucosyltransferase was not expressed.

Thus we conclude that overproduction of protocatechuic acid is possiblein yeast by the expression of A. thaliana UGT89B1 glucosyltransferase.

TABLE 16.1 Oligonuoleotides used in example 16. Oligonucleotide 5′-3′Sequence #1, SEQ ID NO: 50 ATTATCTAGAATGAAAGT TAACGAAGAAAACAAC#2, SEQ ID NO: 51 ATTAGGATCCTTACCACC GTTCTATCTCCATCTTC

Example 17 Construction of S. cerevisiae Expression Vectors ContainingS. bicolor CYP79A1, CYP71E1 and UGT85B1

In order to facilitate correct subcloning into the yeast expressionvectors, the three genes were PCR amplified using primers withextensions which provided the DNA fragments with appropriaterestrictions sites. CYP79A1 (using the plasmid CYP79A1PRT101 astemplate) was amplified with the primer pair SbC79F1S and SbC79R1E.CYP71E1 (using the plasmid CYP71E1pcDNAII as template) was amplifiedwith the primer pair SbC71F1 S and SbC71R1E. Finally, UGT85B1 (using theplasmid pcDNAII-UGT85B1 as template) was amplified with the primer pairSbUDPF1S and SbUDPR1E. Oligonucleotide primers are described in Table17.1.

PCR was performed in the following way: Template DNA was used in theamount of 10 ng per reaction (volume of 50 μl). Primers and dNTPs wereused in a final concentration of μM The three genes were amplified using5 U of pfu polymerase (Stratagene) in a final MgSO₄ concentration of 2mM. The following PCR conditions were used for the amplification:initially 95° C. for 5 minutes, thereafter 35 cycles of 95° C. for 45seconds, Tm for 30 seconds and 72° C. for 90 seconds. Finally, 72° C.for 10 minutes. Tm for CYP79A1 was 62° C., Tm for CYP71E1 was 65° C. andTm for UGT85B 1 was 64° C.

The three amplified genes were initially cloned into pCR-Blunt II TOPO(Invitrogen). Following transformation into E. coli strain DH5α andplasmid isolation using the QIAGEN system (QIAGEN), the integrity of thethree genes was verified by DNA sequencing using appropriate sequencingprimers.

Prior to subcloning into yeast expression vectors the above mentionedthree genes were released from the TOPO vectors by cutting with therestriction enzymes EcoRI and SpeI followed by agarosegel-electrophoresis and DNA recovery using the QIAex system (Qiagen)according to manufactures instructions Similarly, the yeast expressionsvectors were cut with EcoRI and SpeI, treated with SAP and alsorecovered using the QIAex system.

Standard T4 DNA ligase (New England Biolabs) ligation was performed overnight at 16° C., according to manufactures instructions. Followingtransformation into E. coli strain DH5α and plasmid isolation using theQIAGEN system according to manufactures instruction, the integrity ofthe yeast expression constructions was verified by cutting withappropriate restriction enzymes and gel-electrophoresis.

CYP79A1 was cloned into the following plasmid vectors (Mumberg et al.1995, Gene 156:119122): p416-GPD (resulting in p#33A), p426-GPD(resulting in p#34A), p416-TEF (resulting in p#41A) and p426-TEF(resulting in p#42A). CYP71E1 was cloned into the following vectors:p413-GPD (resulting in p#27A), p423-GPD (resulting in p#28A), p413-TEF(resulting in p#35A) and p413-ADH (resulting in p#43A). UGT85B1 wascloned into the vector p415-GPD (resulting in p#S31B).

TABLE 17.1 Oligonucleotide sequence for primers used for cloning. NamePrimer sequence SEQ ID NO: SbC79F1S 5′-agcactagtatggcgacaa 52tggaggtagaggcc-3′ SbC79R1E 5′-agcgaattctcagatggag 53 atggacgggtagagg-3′SbC71F1S 5′-agcactagtatggccacca 54 ccgccaccccgcagctcc-3′ SbC71R1E5′-agcgaattcctaggcggcg 55 cggcggttcttgtatttgg-3′ SbUDPR1E5′-agcgaattctcactgcttg 56 cccccgaccagcagc-3′ SbUDPF1S5-cagcactagtatgggcagca 57 acgcgccgcctcc-3′

Example 18 Construction of S. cerevisiae Strains Expressing S. bicolorCYP79A1, CYP71E1 and UGT85B1 and of Strains Containing Mock Plasmids

Standard yeast transformation by electroporation (Becker and Guarente,1991, Methods in Enzymology 194:182-187) was done in the yeast strainBY4741 (mata his3D1 leu2D0 met15D0 ura3D0) (EUROSCARF).

The following yeast strains (expressing the three S. bicolor genes) wereconstructed by transformation with the above mentioned plasmid andselected on SC-His,Ura,Leu media:

-   -   Y0109 by transformation of BY4741 with the plasmids p#27A, p#33A        and p#S31B.    -   Y0113 by transformation of BY4741 with the plasmids p#28A, p#34A        and p#S31B.    -   Y0117 by transformation of BY4741 with the plasmids p#35A, p#41A        and p#S31B.    -   Y0121 by transformation of BY4741 with the plasmids p#43A, p#42A        and p#S31B.

The following yeast strains (containing mock plasmids) were constructedby transformation with the above mentioned plasmid and selected onSC-His,Ura,Leu media:

-   -   Y0084 by transformation of BY4741 with the plasmids p413-GPD,        p416-GPD and p415-GPD    -   Y0085 by transformation of BY4741 with the plasmids p423-GPD,        p426-GPD and p415-GPD.    -   Y0086 by transformation of BY4741 with the plasmids p413-TEF,        p416-TEF and p415-GPD.    -   Y0087 by transformation of BY4741 with the plasmids p413-ADH,        p426-TEF and p415-GPD.

The following yeast strains (expressing the two S. bicolor genes CYP79A1and CYP71E1) were constructed by transformation with the above mentionedplasmid and selected on SC-His,Ura media:

-   -   Y0091 by transformation of BY4741 with the plasmids p#27A and        p#33A.    -   Y0092 by transformation of BY4741 with the plasmids p#28A and        p#34A.    -   Y0093 by transformation of BY4741 with the plasmids p#35A and        p#41A.    -   Y0094 by transformation of BY4741 with the plasmids p#43A and        p#42A.

The following yeast strains (containing mock plasmids) were constructedby transformation with the above mentioned plasmid and selected onSC-His,Ura media:

-   -   Y0071 by transformation of BY4741 with the plasmids p413-GPD and        p416-GPD.    -   Y0072 by transformation of BY4741 with the plasmids p423-GPD and        p426-GPD.    -   Y0073 by transformation of BY4741 with the plasmids p413-TEE and        p416-TEE.    -   Y0074 by transformation of BY4741 with the plasmids p413-ADH and        p426-TEE

The following yeast strains (expressing the two S. bicolor genes CYP79A1and UGT85B1) were 15 constructed by transformation with the abovementioned plasmid and selected on SC-Ura,Leu media:

-   -   Y0103 by transformation of BY4741 with the plasmids p#33A and        p#S31B.    -   Y0104 by transformation of BY4741 with the plasmids p#34A and        p#S31B.    -   Y0105 by transformation of BY4741 with the plasmids p#41A and        p#S31B.    -   Y0106 by transformation of BY4741 with the plasmids p#42A and        p#S31B.

The following yeast strains (containing mock plasmids) were constructedby transformation with the above mentioned plasmid and selected onSC-Ura, Leu media:

-   -   Y0078 by transformation of BY4741 with the plasmids p416-GPD and        p415-GPD.    -   Y0079 by transformation of BY4741 with the plasmids p426-GPD and        p415-GPD.    -   Y0080 by transformation of BY4741 with the plasmids p416-TEF and        p415-GPD.    -   Y0081 by transformation of BY4741 with the plasmids p426-TEF and        p415-GPD.

Example 19 Propagation of S. cerevisiae Strains Expressing S. bicolorCYP79A1, CYP71E1 and UGT85B1 and of Strains Containing Mock Plasmids

The above mentioned yeast strains were propagated in appropriatesynthetic growth omission media lacking the same amino acids as used forselection of transformed cells. Cells were grown at 28° C., 175 RPM in avolume of 3 ml, until stationary phase. Liquid propagation was performedin 15 ml culture tubes.

Prior to glucose fermentation, the cells of the outgrown cultures wererecovered by centrifugation (4000 RPM for ten minutes), separated fromthe spent media, washed once in synthetic glucose minimal (SD+) drop inmedia (see below), again recovered by centrifugation and finallyresuspended in 3 ml of appropriated SD+ media.

Strains originally selected on SC-His, Ura, Leu were resuspended inSD+Lys, Met. Strains originally selected on SC-His Um were resuspendedin SD+Lys, Met, Leu. Strains originally selected on SC-Ura, Leu wereresuspended in SD+Lys, Met, His.

After resuspension of cells in SD+ media, liquid cultures were kept at28° C., 175 RPM and samples were collected, as described below, forsubsequent LC-MS analysis.

Example 20 Metabolite Analysis of S. cerevisiae Strains Expressing S.bicolor CYP79A1, CYP71E1 and UGT85B1 and of Strains Containing MockPlasmids

In order to analyze the composition of secondary metabolites produced bythe above mentioned yeast strains, samples of 0.5 ml were collected atthe following time points after resuspension in SD+ media: 24 hours, 48hours, 72 hours and 92 hours. In the case of analysis for dhurrin, onlythe time points of 24 and 48 hours were collected.

Samples to be analyzed for total content of a given secondary metabolite(amount of glycosylated and non-glycosylated molecules) will be treatedwith p-glucosidase (Fluka) prior to LC-MS.

Cells were separated from media by centrifugation (4000 RPM for tenminutes). 333 μl of the liquid phase from each sample was dried down invacua, and resuspended in 50 μl of 50° A) MeOH. After centrifugation, at15000 RPM for ten minutes of the MeOH resuspension, 25 was used forcharacterization by LC-MS. Samples were stored at −20° C. prior to LC/MSanalysis.

Appropriate reference samples were manufactured by adding known amountsof the given reference compound to 0.5 ml of media (sampled 48 hoursafter resuspension in SD+ media) obtained from the corresponding yeaststrain carrying mock plasmids. After adding the reference compound tomedia the reference samples were treated as described immediately above.In order to be able to quantify the amount of a given secondarymetabolite, the corresponding reference samples were manufactured intriplicate, varying only in concentration of the reference compound (0.1μg/ml, 1 μg/ml and 10 μg/ml). Finally, in order to uniquely identify theretention time for each particular molecule searched for, one referencesample containing only the given compound was prepared (1 μg/ml in 50%MeOH).

Analytical LC-MS was carried out using an Agilent 1100 Series LC(Agilent Technologies, Germany) coupled to a Bruker Esquire 3000+ iontrap mass spectrometer (Bruker Daltonics, Bremen, Germany). An XTerra MSC18 column (Waters, Milford, Mass., 3.5 μM, 2.1×100 mm) was used at aflow rate of 0.2 mL min⁻¹. The mobile phases were: A, 0.1% (v/v) HCOOHand 50 μM Nag B, 0.1% (v/v) HCOOH and 80% (v/v) MeCN. The gradientprogram was: 0 to 3 min, isocratic 3% (v/v) B; 2 to 30 min, lineargradient 3 to 50% B; 30 to 35 min, linear gradient 50% to 100% (v/v) B;35 to 40 min, isocratic 100% B. The mass spectrometer was configured forelectrospray ionization (ESI) in positive ion mode. Total ion currentand ion traces for specific [M+Na]+ adduct ions were used for locatingcompounds. In the case of aglycone detection the mass spectrometer wasconfigured for Atmospheric Pressure Chemical Ionization (APCI) inpositive ion mode. Spectra were analyzed using Bruker DaltonicsDataanalysis v. 3.1 software (Bruker GmBH)

Quantification of a given secondary metabolite (aglycone or glycosylatedversion thereof) was done by integration of the area of the mass peak(LC-MS) and comparing obtained values to that of the standard curve fromthe three corresponding reference samples spiked with known amounts ofthat particular substance in question.

Example 21 Production of p-Hydroxymancielonitrile-β-D-Glucoside(Dhurrin) by Glucose 5 Fermentation of S. cerevisiae Strains ExpressingS. bicolor CYP79A1, CYP71E1 and UGT85B1

The amount of Dhurrin produced by the yeast strains Y0109, Y0113, Y0117and Y0121 was measured at the following time points. Quantification ofDhurrin was done by regression according to the equation [Dhurrin(ng/ml)]=6E-171^(2,5218) (R4:0,92) were I is the area of the 10 masspeak. This equation was derived from three spiked samples as describedabove.

TABLE 21.1 Dhurrin produced in S. cerevisiae strains expressing S.bicolor CYP79A1, CYP71E1 and UGT85B1. Strain Y0109 Y0113 Y0117 Y0121Time-point ng/ml ng/ml ng/ml ng/ml 24 hours 22.7 562 90.6 0.10 48 hours57.7 945 356 0.06

Retention time for Dhurrin (m/z=334) was 13.6 minutes.

Tracer experiments by use of radio-labeled tyrosine demonstrated thatthe aglucone of dhurrin (p-hydroxymandelonitrile) was not present. It isaccordance with prior art knowledge that explains that the aglucone ofdhurrin is highly unstable in aqueous solutions (Halkier and Mølelr,1989, Plant Journal 90:1552-1559). The glucosylation performed byUGT85B1 results in a virtual unlimited overproduction of this unstablearomatic nitrile. No peak of m/z=334 at 13.6 minutes, exceeding thebackground noise was found in the case of yeast strains carrying mockplasmids (strains Y0084, Y0085, Y0086 and Y0087). In the case of strains(Y0094, Y0095, Y0096 and Y0097) carrying expression plasmids of CYP79A1together with CYP71E1 no peak of m/z=334 at 13.6 minutes exceeding 10ng/ml was found at any time point. Therefore the 945 ng/ml of Dhurrinfound in the case of strain Y0113 after 48 hours of fermentation amountsto a least 94-fold overproduction, as a result of the expression of theglucosyltransferase UGT85B1.

Example 22 Production of Compounds Derived from the Dhurrin BiosynthesisPathway by Expression of S. bicolor CYP79A1, CYP71E1 and UGT85B1

Mass spectra from samples derived from strains expressing S. bicolorCYP79A1, CYP71E1 and UGT85B1 in non-equimolar amounts of gene productsdisplays production of glucosylated molecules derived from intermediatesof the Dhurrin biosynthesis pathway. It is therefore believed thatglycosylation mediated by glycosyltransferases (here UGT85B1 as anexample) can result in the continuous removal of intermediates frombiosynthesis pathways thereby achieving overproduction of a givenaglycone. In Table 22.1 the amounts of various putatively assignedglucosylated compounds derived from the Dhurrin biosynthesis pathway arelisted. Quantification was performed similarly to that of the Dhurrinmeasurements described above, using the same equation.

TABLE 22.1 Glucosylated compounds, other than Dhurrin produced in S.cerevisiae strains expressing S. bicolor CYP79A1, CYP71E1 and UGT85B1.Y010 Y011 Y011 Y012 Y010 Y011 Y011 Y012 Y010 Y011 Y011 Y012 9 3 7 1 9 37 1 9 3 7 1 ng/ml ng/ml ng/ml Strain p-glucosyloxy- p-glucosyloxy-p-glucosyloxy- Time phenylethanol a) phenylacetonitrile benzaldehydepoint m/z = 323 zn/z = 318 m/z = 307 24 361 226 165 408 4.2 4.7 1.7 6.023 0.7 1.5 0.4 hours 48 2606 1134 1830 2759 52 38 98 84 22 5.9 7.8 3.2hours 72 6424 3125 1649 12497 269 118 74 371 65 32 16 18 hours 96 hours4979 4407 2952 15428 288 198 151 784 62 31 22 23

a) Alternatively the m/z=323 ion corresponds to p-glucosyloxy-benzoicacid or glucosyl p-hydroxybenzoate. Retention time ofp-glucosyloxy-phenylethanol was 14.4 minutes. Retention time ofp-glucosyloxy-phenylacetonitrile was 14.4 minutes. Retention time ofp-glucosyloxy-benzaldehyde was 19.7 minutes

Example 23 Overproduction of Compounds Derived from Intermediates of theDhurrin Biosynthesis Pathway by Expression of the S. bicolor GenesCYP79A1, CYP71E1 and UGT85B1 in S. cerevisiae

Unambiguous identification of the above mentioned glucosides areachieved similarly to the method described for dhurrin identificationusing authentic standards for p-glucosyloxy-phenylethanol,p-glucosyloxy-benzoic acid, glucosyl p-hydroxybenzoate,p-glucosyloxy-phenylacetonitrile and p-glucosyloxy-benzaldehyde.

Identification and quantification of aglycone molecules are performed inthe following way:

growth media from strains expressing the Dhurrin biosynthesis genes orfrom strains carrying mock plasmids are collected at the same timepoints and by the same methods as described above. Thereafter the spentmedia are treated with p-glucosidase (to release the aglycones fromtheirs glycoside forms). Again, in order to be able to quantify theamount of a given aglycone, the corresponding reference samples aremanufactured in triplicate, varying only in concentration of thereference compound (0.1 μg/ml, 1 μg/ml and 10 μg/ml). Finally, in orderto uniquely identifying the retention time for each particular moleculesearched for, one of each reference sample containing only the givencompound is prepared (1 μg/ml in 50% MeOH).

Demonstration of overproduction by glucosylation is done by comparisonof the produced amount of the given aglucone (after β-glucosidasetreatment) from strains expressing UGT85B1 together with CYP79A1 (and insome cases also CYP71E1) to that of strains expressing only CYP79A1 (andin some cases also CYP71E1). This procedure demonstrates at least 1.5times overproduction.

REFERENCES

The references mentioned below are a selection of the references thatare considered most pertinent with respect to the present invention.

-   Paquette, S. et al, Phytochemistry 62 (2003) 399-413. WO01/07631.-   WO01/40491-   Arend, J et al., Biotech. & Bioeng (2001) 78:126-131-   Tattersall, D B et al, Science (2001) 293:1826-8 Moehs, C P et al,    Plant Journal (1997) 11:227-236 U.S. Pat. No. 6,372,461

We claim:
 1. A method of producing a low molecular weight organicaglycon compound comprising following steps: a) fermenting amicroorganism cell in a suitable medium where the microorganism iscapable of growing, which comprises a gene encoding a product involvedin the biosynthesis pathway leading to a low molecular weight organicaglycon compound and a glycosyltransferase gene encoding aglycosyltransferase capable of glycosylating the produced aglycon, undersuitable conditions wherein the cell produces the aglycon and thecorresponding glycosylated form of the aglycon; b) deglycosylating theglycosylated form of the aglycon; and c) recovering the aglyconcompound; (i) wherein the low molecular weight organic aglycon compoundhas a molecular weight from 50 to 3000, and (ii) wherein theglycosyltransferase is a glycosyltransferase capable of conjugating asugar to the aglycon compound.
 2. The method of claim 1, wherein themicroorganism cell with the glycosyltransferase during culturefermentation is capable of producing higher amounts of the glycosylatedform of the aglycon as compared to the amounts of the correspondingaglycon produced by the same microorganism cell without theglycosyltransferase.
 3. The method of claim 2, wherein the microorganismcell is a yeast cell.
 4. The method of claim 3, wherein the yeast cellis a Saccharomyces spp. cell or a Pichia spp. cell.
 5. The method ofclaim 2, wherein the microorganism cell is a prokaryotic cell.
 6. Themethod of claim 5, wherein the prokaryotic cell is an E. coli cell. 7.The method of claim 1, wherein the glycosyltransferase gene is aheterologous glycosyltransferase gene.
 8. The method of claim 1, whereinthe glycosyltransferase is an UDPG glycosyltransferase, preferably anUDPG-glucosyltransferase.
 9. The method of claim 1, wherein the lowmolecular weight organic aglycon compound is an organic aglycon compoundthat comprises a compound that contains a Hydroxy-, Amino-, Sulfide-, orCarboxy functional group that can be glycosylated by use of theglycosyltransferase.
 10. The method of claim 9, wherein the lowmolecular weight organic aglycon compound is an organic aglycon compoundthat comprises a compound that contains Hydroxy-functional group, or analcohol, that can be glycosylated by use of the glycosyltransferase. 11.The method of claim 9, wherein the aglycon compound has a molecularweight from 50 to 1000 kilodaltons.
 12. The method of claim 11, whereinthe aglycon compound is a secondary metabolite compound.
 13. The methodof claim 12, wherein secondary metabolite compound is a plant secondarymetabolite compound selected from the group consisting of Terpenoids,Alkaloids, Phenylpropanoids, Phenyl derivatives, Hexanol derivatives,Flavonoids, Coumarins, Stilbenes, Cyanohydrins, and Glucosinolates. 14.The method of claim 13, wherein the plant secondary metabolite organicaglycon compound is vanillin.
 15. The method of claim 14, wherein themicroorganism cell is a yeast cell.
 16. The method of claim 15, whereinthe yeast cell is a Saccharomyces spp. cell or a Pichia spp. cell. 17.The method of claim 14, wherein the microorganism cell is a prokaryoticcell.
 18. The method of claim 17, wherein the prokaryotic cell is an E.coli cell.
 19. The method of claim 1, wherein the deglycosylating stepb) takes place outside the growing cell following excretion orextraction of the glycosylated form of the aglycon produced in step a)and wherein the deglycosylating is an enzymatic process mediated by abeta-glucosidase.